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Louis Pasteur in his laboratory 
By permission, from the painting by Albert Edelfelt 



THE HARVARD CLASSICS 

EDITED BY CHARLES W ELIOT LL D 



« 



SCIENTIFIC PAPERS 

PHYSIOLOGY •■ MEDICINE • SURGERY 
GEOLOGY 

WITH INTRODUCTIONS AND NOTES 
VOLUME 38 




P F COLLIER & SON COMPANY 
NEW YORK 



A 
I 

3% 



Copyright, 1897 
By G. P. Putnam's Sons 

Entered at Stationers' Hall, London 

Copyright, 1861, 1862, 1883, 1889, 1890, 1S91 
By Oliver Wendell Holmes 

Copyright, 1892 

By Houghton, Mifflin & Company 

All Rights Reserved 

Copyright, 1910 
By P. P. Collier & Son 

MANUFACTURED IN U. S. A. 



CONTENTS 

FAGS 

The Oath of Hippocrates . . ♦ . . . » • # r» 3 
The Law of Hippocrates ........... 4 

Journeys in Diverse Places .... Ambroise ParI 9 
translated by stephen paget 

On the Motion of the Heart and Blood in Animals . 65 
William Harvey . . . translated by Robert willis 

The Three Original Publications On Vaccination 

Against Smallpox Edward Jenner 153 

The Contagiousness of Puerperal Fever 233 

O. W. Holmes 

On the Antiseptic Principle of the Practice of Surgery 271 

Lord Lister 

The Physiological Theory of Fermentation .... 289 

Louis Pasteur 

TRANSLATED BY F. FAULKNER AND D. C R0B3 (Revised) 

The Germ Theory and its Applications to MrciciNE and 

Surgery (Revised) Louis Pasteur 382 

translated by h. c ernst 

On the Extension of the Germ Theory to the Etiology 
of Certain Common Diseases (Revised) Louis Pasteur 391 

translated by h. c ernst 

Prejudices which have Retarded the Progress of 

Geology Sir Charles Lyell 405 

Uniformity in the Series of Past Changes in the 
Animate and Inanimate World Sir Charles Lyell 419 

1 

(U HQ— Vol. 3S 



INTRODUCTORY NOTE 

Hippocrates, the celebrated Greek physician, was a contempo- 
rary of the historian Herodotus. He was born in the island of 
Cos between 4/0 and 460 B. C, and belonged to the family thai 
claimed descent from the mythical Msculapius, son of Apollo. 
There was already a long medical tradition in Greece before his 
day, and this he is supposed to have inherited chiefly through his 
predecessor Herodicus; and he enlarged his education by ex- 
tensive travel. He is said, though the evidence is unsatisfactory, 
to have taken part in the efforts to check the great plague which 
devastated Athens at the beginning of the Peloponnesian war. 
He died at Larissa between 380 and 360 B. C. 

The works attributed to Hippocrates are the earliest extant 
Greek medical writings, but very many of them are certainly not 
his. Some five or six, however, are generally granted to be 
genuine, and among these is the famous "Oath." This interesting 
document shows that in his time physicians were already organised 
into a corporation or guild, with regulations for the training of 
disciples, and with an esprit de corps and a professional ideal 
which, with slight exceptions, can hardly yet be regarded as 
out of date. 

One saying occurring in the words of Hippocrates has achieved 
universal currency, though few who quote it to-day are aware 
that it originally referred to the art of the physician. It is the 
first of his "Aphorisms": "Life is short, and the Art long; the 
occasion fleeting; experience fallacious, and judgment difficult. 
The physician must not only be prepared to do what is right 
himself, but also to make the patient, the attendants, and ex* 
ternals cooperate." 



THE OATH OF HIPPOCRATES 

I SWEAR by Apollo the physician and .ZEsculapius, and 
Health, and All-heal, and all the gods and goddesses, 
that, according to my ability and judgment, I will keep 
this Oath and this stipulation — to reckon him who taught me 
this Art equally dear to me as my parents, to share my sub- 
stance with him, and relieve his necessities if required; to 
look upon his offspring in the same footing as my own 
brothers, and to teach them this art, if they shall wish to 
learn it, without fee or stipulation; and that by precept, 
lecture, and every other mode of instruction, I will impart 
a knowledge of the Art to my own sons, and those of my 
teachers, and to disciples bound by a stipulation and oath 
according to the law of medicine, but to none others. I will 
follow that system of regimen which, according to my ability 
and judgment, I consider for the benefit of my patients, and 
abstain from whatever is deleterious and mischievous. I 
will give no deadly medicine to any one if asked, nor sug- 
gest any such counsel; and in like manner I will not give 
to a woman a pessary to produce abortion. With purity and 
with holiness I will pass my life and practice my Art. I 
will not cut persons labouring under the stone, but will leave 
this to be done by men who are practitioners of this work. 
Into whatever houses I enter, I will go into them for the 
benefit of the sick, and will abstain from every voluntary 
act of mischief and corruption; and, further, from the se- 
duction of females or males, of freemen and slaves. What- 
ever, in connection with my professional practice, or not in 
connection with it, I see or hear, in the life of men, which 
ought not to be spoken of abroad, I will not divulge, as 
reckoning that all such should be kept secret. While I con- 
tinue to keep this Oath unviolated, may it be granted to me 
to enjoy life and the practice of the art, respected by all 
men, in all times. But should I trespass and violate this 
Oath, may the reverse be my lot 

3 



THE LAW OF HIPPOCRATES 

MEDICINE is of all the arts the most noble; but, 
owing to the ignorance of those who practice it, and 
of those who, inconsiderately, form a judgment of 
them, it is at present far behind all the other arts. Their 
mistake appears to me to arise principally from this, that 
in the cities there is no punishment connected with the 
practice of medicine (and with it alone) except disgrace, 
and that does not hurt those who are familiar with it. Such 
persons are like the figures which are introduced in trage- 
dies, for as they have the shape, and dress, and personal 
appearance of an actor, but are not actors, so also phy- 
sicians are many in title but very few in reality. 

2. Whoever is to acquire a competent knowledge of medi- 
cine, ought to be possessed of the following advantages: a 
natural disposition; instruction; a favorable position for the 
study ; early tuition ; love of labour ; leisure. First of all, a 
natural talent is required; for, when Nature leads the way 
to what is most excellent, instruction in the art takes place, 
which the student must try to appropriate to himself by re- 
flection, becoming an early pupil in a place well adapted for 
instruction. He must also bring to the task a love of labour 
and perseverance, so that the instruction taking root may 
bring forth proper and abundant fruits. 

3. Instruction in medicine is like the culture of the pro- 
ductions of the earth. For our natural disposition, is, as it 
were, the soil ; the tenets of our teacher are, as it were, the 
seed; instruction in youth is like the planting of the seed 
in the ground at the proper season; the place where the 
instruction is communicated is like the food imparted to 
vegetables by the atmosphere ; diligent study is like the culti- 
vation of the fields; and it is time which imparts strength 
to all things and brings them to maturity. 

4. Having brought all the?e requisites to the study of 
medicine, and having acquired a true knowledge of it, we 

4 



THE LAW S 

shall thus, in travelling through the cities, be esteemed phy- 
sicians not only in name but in reality. But inexperience is 
a bad treasure, and a bad fund to those who possess it, 
whether in opinion or reality, being devoid of self-reliance 
and contentedness, and the nurse both of timidity and au- 
dacity. For timidity betrays a want of powers, and audacity 
a lack of skill. They are, indeed, two things, knowledge and 
opinion, of which the one makes its possessor really to know, 
the other to be ignorant. 

5. Those things which are sacred, are to be imparted only 
to sacred persons; and it is not lawful to impart them to 
the profane until they have been initiated in the mysteries 
of the science. 




VACCINATION 
AGAINST SMALLPOX 



An Inquiry into the Causes and Effects of the 
Variola Vaccina, or Cow-Pox. 1798 

I HE deviation of man from the stage in which he was 
originally placed by nature seems to have proved to 
him a prolific source of diseases. From the love of 
splendour, from the indulgences of luxury, and from his 
fondness for amusement he has familiarised himself with 
a great number of animals, which may not originally have 
been intended for his associates. 

The wolf, disarmed of ferocity, is now pillowed in the 
lady's lap. 1 The cat, the little tiger of our island, whose 
natural home is the forest, is equally domesticated and 
caressed. The cow, the hog, the sheep, and the horse, are 
all, for a variety of purposes, brought under his care and 
dominion. 

There is a disease to which the horse, from his state of 
domestication, is frequently subject. The farriers have 
called it the grease. It is an inflammation and swelling in 
the heel, from which issues matter possessing properties of 
a very peculiar kind, which seems capable of generating a 
disease in the human body (after it has undergone the 
modification which I shall presently speak of), which bears 
so strong a resemblance to the smallpox that I think it 
highly probable it may be the source of the disease. 

In this dairy country a great number of cows are kept, 
and the office of milking is performed indiscriminately by 

1 The late Mr. John Hunter proved, by experiments, that the dog is the 
Wolf in a degenerate state. 

1S3 



154 EDWARD JENNER 

men and maid servants. One of the former having been 
appointed to apply dressings to the heels of a horse affected 
with the grease, and not paying due attention to cleanliness, 
incautiously bears his part in milking the cows, with some 
particles of the infectious matter adhering to his fingers. 
When this is the case, it commonly happens that a disease 
is communicated to the cows, and from the cows to the 
dairymaids, which spreads through the farm until the most 
of the cattle and domestics feel its unpleasant consequences. 
This disease has obtained the name of the cow-pox. It 
appears on the nipples of the cows in the form of irregular 
pustules. At their first appearance they are commonly of a 
palish blue, or rather of a colour somewhat approaching to 
livid, and are surrounded by an erysipelatous inflammation. 
These pustules, unless a timely remedy be applied, frequently 
degenerate into phagedenic ulcers, which prove extremely 
troublesome. 3 The animals become indisposed, and the 
secretion of milk is much lessened. Inflamed spots now 
begin to appear on different parts of the hands of the do- 
mestics employed in milking, and sometimes on the wrists, 
which quickly run on to suppuration, first assuming the 
appearance of the small vesications produced by a burn. 
Most commonly they appear about the joints of the fingers 
and at their extremities; but whatever parts are affected, 
if the situation will admit, these superficial suppurations put 
on a circular form, with their edges more elevated than their 
centre, and of a colour distantly approaching to blue. 
Absorption takes place, and tumours appear in each axilla. 
The system becomes affected — the pulse is quickened; and 
shiverings, succeeded by heat, with general lassitude and 
pains about the loins and limbs, with vomiting, come on. 
The head is painful, and the patient is now and then even 
affected with delirium. These symptoms, varying in their 
degrees of violence, generally continue from one day to 
three or four, leaving ulcerated sores about the hands, which, 
from the sensibility of the parts, are very troublesome, and 
commonly heal slowly, frequently becoming phagedenic, like 

2 They who attend sick cattle in this country find a speedy remedy for 
stopping the progress of this complaint in those applications which act chem ; 
ically upon the morbid matter, such as the solutions of the vitriolum zinci 
and the vitriolum cupri, etc. 



VACCINATION AGAINST SMALLPOX 155 

those from whence they sprung. The lips, nostrils, eyelids, 
and other parts of the body are sometimes affected with 
sores; but these evidently arise from their being heedlessly 
rubbed or scratched with the patient's infected fingers. No 
eruptions on the skin have followed the decline of the 
feverish symptoms in any instance that has come under my 
inspection, one only excepted, and in this case a very few 
appeared on the arms: they were very minute, of a vivid 
red colour, and soon died away without advancing to matur- 
ation; so that I cannot determine whether they had any 
connection with the preceding symptoms. 

Thus the disease makes its progress from the horse 8 to 
the nipple of the cow, and from the cow to the human 
subject. 

Morbid matter of various kinds, when absorbed into the 
system, may produce effects in some degree similar; but 
what renders the cow-pox virus so extremely singular is 
that the person who has been thus affected is forever after 
secure from the infection of the smallpox; neither exposure 
to the variolous effluvia, nor the insertion of the matter into 
the skin, producing this distemper. 

In support of so extraordinary a fact, I shall lay before 
my reader a great number of instances.* 

Case I. — Joseph Merret, now an under gardener to the 
Earl of Berkeley, lived as a servant with a farmer near this 
place in the year 1770, and occasionally assisted in milking 
his master's cows. Several horses belonging to the farm 

8 Jenner's conclusion that " grease " and cow-pox were the same disease 
has since been proved erroneous; but this error has not invalidated his 
main conclusion as to the relation of cow-pox and smallpox. — Editor. 

* It is necessary to observe that pustulous sores frequently appear spon- 
taneously on the nipples of cows, and instances have occurred, though very 
rarely, of the hands of the servants employed in milking being affected with 
sores in consequence, and even of their feeling an indisposition from ab- 
sorption. These pustules are of a much milder nature than those which 
arise from that contagion which constitutes the true cow-pox. They sre 
always free from the bluish or livid tint so conspicuous in the pustules in 
that disease. No erysipelas attends them, nor do they shew any phagedenic 
disposition as in the other case, but quickly terminate in a scab without 
creating any apparent disorder in the cow. This complaint appears at vari- 
ous seasons of the year, but most commonly in the spring, when the cows 
are first taken from their winter food and fed with grass. _ It is very apt 
to appear also when they are suckling their young. But this disease is not 
to be considered as similar in any respect to that of which I am treating, 
as it is incapable of producing any specific effects on the human constitution. 
However, it is of the greatest consequence to point it out here, lest the 
want of discrimination should occasion an idea of security from the infec- 
tion of the smallpox, which might prove delusive. 



156 EDWARD JENNER 

began to have sore heels, which Merret frequently attended. 
The cows soon became affected with the cow-pox, and soon 
after several sores appeared on his hands. Swellings and 
stiffness in each axilla followed, and he was so much indis- 
posed for several days as to be incapable of pursuing his 
ordinary employment. Previously to the appearance of the 
distemper among the cows there was no fresh cow brought 
into the farm, nor any servant employed who was affected 
with the cow-pox. 

In April, 1795, a general inoculation taking place here, 
Merret was inoculated with his family; so that a period of 
twenty-five years had elapsed from his having the cow-pox 
to this time. However, though the variolous matter was 
repeatedly inserted into his arm, I found it impracticable to 
infect him with it ; an efflorescence only, taking on an erysip- 
elatous look about the centre, appearing on the skin near the 
punctured parts. During the whole time that his family had 
the smallpox, one of whom had it very full, he remained in 
the house with them, but received no injury from exposure 
to the contagion. 

It is necessary to observe that the utmost care was taken 
to ascertain, with the most scrupulous precision, that no one 
whose case is here adduced had gone through the smallpox 
previous to these attempts to produce that disease. 

Had these experiments been conducted in a large city, or 
in a populous neighbourhood, some doubts might have been 
entertained; but here, where population is thin, and where 
such an event as a person's having had the smallpox is 
always faithfully recorded, no risk of inaccuracy in this 
particular can arise 

Case II. — Sarah Portlock, of this place, was infected with 
the cow-pox when a servant at a farmer's in the neighbour- 
hood, twenty-seven years ago. 6 

In the year 1792, conceiving herself, from this circum- 
stance, secure from the infection of the smallpox, she nursed 
one of her own children who had accidentally caught the 

5 I have purposely selected several cases in which the disease had appeared 
at a very distant period previous to the experiments < made with variolous 
matter, to shew that the change produced in the constitution is not affected 
by time. 



VACCINATION AGAINST SMALLPOX 157 

disease, but no indisposition ensued. During the time she 
remained in the infected room, variolous matter was inserted 
into both her arms, but without any further effect than in 
the preceding case. 

Case III. — John Phillips, a tradesman of this town, had 
the cow-pox at so early a period as nine years of age. At 
the age of sixty-two I inoculated him, and was very careful 
in selecting matter in its most active state. It was taken 
from the arm of a boy just before the commencement of the 
eruptive fever, and instantly inserted. It very speedily pro- 
duced a sting-like feel in the part. An efflorescence appear- 
ed, which on the fourth day was rather extensive, and some 
degree of pain and stiffness were felt about the shoulder: but 
on the fifth day these symptoms began to disappear, and in 
a day or two after went entirely off, without producing any 
effect on the system. 

Case IV. — Mary Barge, of Woodford, in this parish, was 
inoculated with variolous matter in the year 1791. An 
efflorescence of a palish red colour soon appeared about the 
parts where the matter was inserted, and spread itself rather 
extensively, but died away in a few days without producing 
any variolous symptoms. 8 She has since been repeatedly 
employed as a nurse to smallpox patients, without expe- 
riencing any ill consequences. This woman had the cow- 
pox when she lived in the service of a farmer in this parish 
thirty-one years before. 

Case V. — Mrs. K , a respectable gentlewoman of this 

town, had the cow-pox when very young. She received the 
infection in rather an uncommon manner: it was given by 
means of her handling some of the same utensils 7 which 

J It is remarkable that variolous matter, when the system is disposed to 
reject it, should excitfc inflammation on the part to which it is applied more 
speedily than when it produces the smallpox. Indeed, it becomes almost 
a criterion by which we can determine whether the infection will be received 
or not.^ It seems as if a change, which endures through life, had been pro- 
duced in the action, or disposition to action, in the vessels ui the skin; and 
it is remarkable, too, that whether this change has been effected by the 
smallpox or the cow-pox that the disposition to sudden cuticular inflamma- 
tion is the same on the application of variolous matter. 

7 When the cow-pox has prevailed in the dairy, it has often been communi- 
cated to those who have not milked the cows, by the handle of the milk pail. 



15S EDWARD JENNER 

were in use among the servants of the family, who had the 
disease from milking infected cows. Her hands had many 
of the cow-pox sores upon them, and they were communi- 
cated to her nose, which became inflamed and very much 

swollen. Soon after this event Mrs. H was exposed to 

the contagion of the smallpox, where it was scarcely pos- 
sible for her to have escaped, had she been susceptible of it, 
as she regularly attended a relative who had the disease in 
so violent a degree that it proved fatal to him. 
In the year 1778 the smallpox prevailed very much at 

Berkeley, and Mrs. H , not feeling perfectly satisfied 

respecting her safety (no indisposition having followed her 
exposure to the smallpox), I inoculated her with active 
variolous matter. The same appearance followed as in the 
preceding cases — an efflorescence on the arm without any 
effect on the constitution. 

Case VI. — It is a fact so well known among our dairy 
farmers that those who have had the smallpox either escape 
the cow-pox or are disposed to have it slightly, that as soon 
as the complaint shews itself among the cattle, assistants are 
procured, if possible, who are thus rendered less susceptible 
of it, otherwise the business of the farm could scarcely go 
forward. 

In the month of May, 1796, the cow-pox broke out at Mr. 
Baker's, a farmer who lives near this place. The disease 
was communicated by means of a cow which was purchased 
in an infected state at a neighbouring fair, and not one of 
the farmer's cows (consisting of thirty) which were at that 
time milked escaped the contagion. The family consisted of 
a man servant, two dairymaids, and a servant boy, who, with 
the farmer himself, were twice a day employed in milking 
the cattle. The whole of this family, except Sarah Wynne, 
one of the dairymaids, had gone through the smallpox. The 
consequence was that the farmer and the servant boy escaped 
the infection of the cow-pox entirely, and the servant man 
and one of the maid servants had each of them nothing 
more then a sore on one of their fingers, which produced 
no disorder in the system. But the other dairymaid, Sarah 
Wynne, who never had the smallpox, did not escape in so 



VACCINATION AGAINST SMALLPOX 159 

easy a manner. She caught the complaint from the cows, 
and was affected with the symptoms described on page 
154 in so violent a degree that she was confined to her bed, 
and rendered incapable for several days of pursuing her 
ordinary vocations in the farm. 

March 28, 1797, I inoculated this girl and carefully rubbed 
the variolous matter into two slight incisions made upon the 
left arm. A little inflammation appeared in the usual man- 
ner around the parts where the matter was inserted, but so 
early as the fifth day it vanished entirely without producing 
any effect on the system. 

Case VII. — Although the preceding history pretty clearly 
evinces that the constitution is far less susceptible of the 
contagion of the cow-pox after it has felt that of the small- 
pox, and although in general, as I have observed, they who 
have had the smallpox, and are employed in milking cows 
which are infected with the cow-pox, either escape the dis- 
order, or have sores on the hands without feeling any gen- 
eral indisposition, yet the animal economy is subject to some 
variation in this respect, which the following relation will 
point out: 

In the summer of the year 1796 the cow-pox appeared at 
the farm of Mr. Andrews, a considerable dairy adjoining to 
the town of Berkeley. It was communicated, as in the pre- 
ceding instance, by an infected cow purchased at a fair in 
the neighbourhood. The family consisted of the farmer, his 
wife, two sons, a man and a maid servant; all of whom, 
except the farmer (who was fearful of the consequences), 
bore a part in milking the cows. The whole of them, exclu- 
sive of the man servant, had regularly gone through the 
smallpox; but in this case no one who milked the cows 
escaped the contagion. All of them had sores upon their 
hands, and some degree of general indisposition, preceded 
by pains and tumours in the axillae: but there was no com- 
parison in the severity of the disease as it was felt by the 
servant man, who had escaped the smallpox, and by those of 
the family who had not, for, while he was confined to his 
bed, they were able, without much inconvenience, to follow 
their ordinary business. 



160 EDWARD JENNER 

February the 13th, 1797, I availed myself of an opportu- 
nity of inoculating William Rodway, the servant man above 
alluded to. Variolous matter was inserted into both his 
arms : in the right, by means of superficial incisions, and into 
the left by slight punctures into the cutis. Both were per- 
ceptibly inflamed on the third day. After this the inflam- 
mation about the punctures soon died away, but a small 
appearance of erysipelas was manifest about the edges of 
the incisions till the eighth day, when a little uneasiness 
was felt for the space of half an hour in the right axilla. 
The inflammation then hastily disappeared without produc- 
ing the most distant mark of affection of the system. 

Case VIII. — Elizabeth Wynne, aged fifty-seven, lived as 
a servant with a neighbouring farmer thirty-eight years ago. 
She was then a dairymaid, and the cow-pox broke out among 
the cows. She caught the disease with the rest of the family, 
but, compared with them, had it in a very slight degree, one 
very small sore only breaking out on the little finger of her 
left hand, and scarcely any perceptible indisposition follow- 
ing it. 

As the malady had shewn itself in so slight a manner, 
and as it had taken place at so distant a period of her life, 
I was happy with the opportunity of trying the effects of 
variolous matter upon her constitution, and on the 28th of 
March, 1797, I inoculated her by making two superficial 
incisions on the left arm, on which the matter was cautiously 
rubbed. A little efflorescence soon appeared, and a tingling 
sensation was felt about the parts where the matter was 
inserted until the third day, when both began to subside, and 
so early as the fifth day it was evident that no indisposition 
would follow. 

Case IX. — Although the cow-pox shields the constitution 
from the smallpox, and the smallpox proves a protection 
against its own future poison, yet it appears that the human 
body is again and again susceptible of the infectious matter 
of the cow-pox, as the following history will demonstrate. 

William Smith, of Pyrton in this parish, contracted this 
disease when he lived with a neighbouring farmer in the 



VACCINATION AGAINST SMALLPOX 161 

year 1780. One of. the horses belonging to the farm had 
sore heels, and it fell to his lot to attend him. By these 
means the infection was carried to the cows, and from the 
cows it was communicated to Smith. On one of his hands 
were several ulcerated sores, and he was affected with such 
symptoms as have been before described 

In the year 1791 the cow-pox broke out at another farm 
where he then lived as a servant, and he became affected with 
it a second time ; and in the year 1794 he was so unfortunate 
as to catch it again. The disease was equally as severe the 
second and third time as it was on the first. 8 

In the spring of the year 1795 he was twice inoculated, 
but no affection of the system could be produced from the 
variolous matter ; and he has since associated with those who 
had the smallpox in its most contagious state without feeling 
any effect from it. 

Case X. — Simon Nichols lived as a servant with Mr. 
Bromedge, a gentleman who resides on his own farm in this 
parish, in the year 1782. He was employed in applying 
dressings to the sore heels of one of his master's horses, 
and at the same time assisted in milking the cows. The cows 
became affected in consequence, but the disease did not shew 
itself on their nipples till several weeks after he had begun 
to dress the horse. He quitted Mr. Bromedge's service, and 
went to another farm without any sores upon him ; but here 
his hands soon began to be affected in the common way, and 
he was much indisposed with the usual symptoms. Con- 
cealing the nature of the malady from Mr. Cole, his new 
master, and being there also employed in milking, the cow- 
pox was communicated to the cows. 

Some years afterward Nichols was employed in a farm 
where the smallpox broke out, when I inoculated him with 
several other patients, with whom he continued during the 
whole time of their confinement. His arm inflamed, but 
neither the inflammation nor his associating with the in- 
oculated family produced the least effect upon his con- 
stitution. 

8 This is not the case in general — a second attack is commonly very slight* 
and so, I am informed, it is among the cows. 

(6) HC— vol. 38 



162 EDWARD JENNER 

Case XI. — William Stinchcomb was a fellow servant with 
Nichols at Mr. Bromedge's farm at the time the cattle had 
the cow-pox, and he was, unfortunately, infected by them. 
His left hand was very severely affected with several cor- 
roding ulcers, and a tumour of considerable size appeared in 
the axilla of that side. His right hand had only one small 
tumour upon it, and no sore discovered itself in the corre- 
sponding axilla. 

In the year 1792 Stinchcomb was inoculated with variolous 
matter, but no consequences ensued beyond a little inflam- 
mation in the arm for a few days. A large party were in- 
oculated at the same time, some of whom had the disease 
in a more violent degree than is commonly seen from inocu- 
lation. He purposely associated with them, but could not 
receive the smallpox. 

During the sickening of some of his companions their 
symptoms so strongly recalled to his mind his own state 
when sickening with the cow-pox that he very pertinently 
remarked their striking similarity. 

Case XII. — The paupers of the village of Tortworth, in 
this county, were inoculated by Mr. Henry Jenner, Surgeon, 
of Berkeley, in the year 1795. Among them, eight patients 
presented themselves who had at different periods of their 
lives had the cow-pox. One of them, Hester Walkley, I 
attended with that disease when she lived in the service of a 
farmer in the same village in the year 1782 ; but neither this 
woman, nor any other of the patients who had gone through 
the cow-pox, received the variolous infection either from 
the arm or from mixing in the society of the other patients 
who were inoculated at the same time. This state of security 
proved a fortunate circumstance, as many of the poor women 
were at the same time in a state of pregnancy. 

Case XIII. — One instance has occurred to me of the 
system being affected from the matter issuing from the 
heels of horses, and of its remaining afterwards unsuscep- 
tible of the variolous contagion; another, where the small- 
pox appeared obscurely; and a third, in which its complete 
existence was positively ascertained. 



VACCINATION AGAINST SMALLPOX 163 

First, Thomas Pearce is the son of a smith and farrier 
near to this place. He never had the cow-pox; but, in con- 
sequence of dressing horses with sore heels at his father's, 
when a lad, he had sores on his fingers which suppurated, 
and which occasioned a pretty severe indisposition. Six 
years afterwards I inserted variolous matter into his arm 
repeatedly, without being able to produce any thing more 
than slight inflammation, which appeared very soon after 
the matter was applied, and afterwards I exposed him to 
the contagion of the smallpox with as little effect. 8 

Case XIV. — Secondly, Mr. James Cole, a farmer in this 
parish, had a disease from the same source as related in the 
preceding case, and some years after was inoculated with 
variolous matter. He had a little pain in the axilla and felt 
a slight indisposition for three or four hours. A few erup- 
tions shewed themselves on the forehead, but they very soon 
disappeared without advancing to maturation. 

Case XV. — Although in the former instances the system 
seemed to be secured, or nearly so, from variolous infection, 
by the absorption of matter from the sores produced by the 
diseased heels of horses, yet the following case decisively 
proves that this cannot be entirely relied upon until a disease 
has been generated by the morbid matter from the horse on 
the nipple of the cow, and passed through that medium to 
the ^luman subject. 

Mr. Abraham Riddiford, a farmer at Stone in this parish, 
in consequence of dressing a mare thit had sore heels, was 
affected with very painful sores in both his hands, tumours 
in each axilla, and severe and general indisposition. A sur- 
geon in the neighbourhood attended him, who knowing the 
similarity between the appearance of the sores upon his 
hands and those produced by the cow-pox, and being 
acquainted also with the effects of that disease on the human 
constitution, assured him that hz never need to fear the in- 
fection of the smallpox; but this assertion proved fallacious, 

f It is a remarkable fact, and well known to many, that we are frequently 
foiled in our endeavours to communicate the smallpox by inoculation to 
blacksmiths, who in the country are farriers. They often, as in the above 
instance, either resist the contagion entirely, or have the disease anoma- 
lously. Shall we not be able to account for this on a rational principle? 



164 EDWARD JENNER 

for, on being exposed to the infection upwards of twenty 
years afterwards, he caught the disease, which took its 
regular course in a very mild way. There certainly was a 
difference perceptible, although it is not easy to describe it, 
in the general appearance of the pustules from that which 
we commonly see. Other practitioners who visited the 
patient at my request agreed with me in this point, though 
there was no room left for suspicion as to the reality of the 
disease, as I inoculated some of his family from the pustules, 
who had the smallpox, with its usual appearances, in conse- 
quence. 

Case XVI. — Sarah Nelmes, a dairymaid at a farmer's 
near this place, was infected with the cow-pox from her 
master's cows in May, 1796. She received the infection on 
a part of her hand which had been previously in a slight 
degree injured by a scratch from a thorn. A large pustulous 
sore and the usual symptoms accompanying the disease were 
produced in consequence. The pustule was so expressive of 
the true character of the cow-pox, as it commonly appears 
upon the hand, that I have given a representation of it in 
the annexed plate. The two small pustules on the wrists 
arose also from the application of the virus to some minute 
abrasions of the cuticle, but the livid tint, if they ever had 
any, was not conspicuous at the time I saw the patient. The 
pustule on the forefinger shews the disease in an earlier 
stage. It did not actually appear on the hand of this young 
woman, but was taken from that of another, and is annexed 
for the purpose of representing the malady after it has newly 
appeared. 

Case XVII. — The more accurately to observe the progress 
of the infection I selected a healthy boy, about eight years 
old, for the purpose of inoculation for the cow-pox. The 
matter was taken from a sore on the hand of a dairymaid, 1 * 
who was infected by her master's cows, and it was inserted, 
on the 14th of May, 1796, into the arm of the boy by means 
of two superficial incisions, barely penetrating the cutis, each 
about half an inch long. 

"From the sore on the hand ot Sarah Nelmes. See the preceding case. 



VACCINATION AGAINST SMALLPOX 165 

On the seventh day he complained of uneasiness in the 
axilla, and on the ninth he became a little chilly, lost his 
appetite, and had a slight headache. During the whole of 
this day he was perceptibly indisposed, and spent the night 
with some degree of restlessness, but on the day following 
he was perfectly well. 

The appearance of the incisions in their progress io a 
state of maturation were much the same as when produced 
in a similar manner by variolous matter. The only difference 
which I perceived was in the state of the limpid fluid arising 
from the action of the virus, which assumed rather a darker 
hue, and in that of the efflorescence spreading round the in- 
cisions, which had more of an erysipelatous look than we 
commonly perceive when variolous matter has been made 
use of in the same manner; but the whole died away (leaving 
on the inoculated parts scabs and subsequent eschars) with- 
out giving me or my patient the least trouble. 

In order to ascertain whether the boy, after feeling so 
slight an affection of the system from the cow-pox virus, was 
secure from the contagion of the smallpox, he was inoculated 
the 1st of July following with variolous matter, immediately 
taken from a pustule. Several slight punctures and incisions 
were made on both his arms, and the matter was carefully 
inserted, but no disease followed. The same appearances 
were observable on the arms as we commonly see when a 
patient has had variolous matter applied, after having either 
the cow-pox or smallpox. Several months afterwards he 
was again inoculated with variolous matter, but no sensible 
effect was produced on the constitution. 

Here my researches were interrupted till the spring of 
the year 1798, when, from the wetness of the early part of 
the season, many of the farmers' horses in this neighbour- 
hood were affected with sore heels, in consequence of which 
the cow-pox broke out among several of our dairies, which 
afforded me an opportunity of making further observations 
upon this curious disease. 

A mare, the property of a person who keeps a dairy in a 
neighbouring parish, began to have sore heels the latter end 
of the month of February, 179S, which were occasionally 
washed by the servant men of the farm, Thomas Virgoe, 



186 EDWARD JENNER 

William Wherret, and William Haynes, who in consequence 
became affected with sores in their hands, followed by in- 
flamed lymphatic glands in the arms and axillae, shiverings 
succeeded by heat, lassitude, and general pains in the limbs. 
A single parox3^sm terminated the disease; for within 
twenty-four hours they were free from general indisposi- 
tion, nothing remaining but the sores on their hands. Haynes 
and Virgoe, who had gone through the smallpox from inocu- 
lation, described their feelings as very similar to those which 
affected them on sickening with that malady. Wherret never 
had had the smallpox. Haynes was daily employed as one 
of the milkers at the farm, and the disease began to shew 
itself among the cows about ten days after he first assisted 
in washing the mare's heels. Their nipples became sore in 
the usual way, with bluish pustules; but as remedies were 
early applied, they did not ulcerate to any extent. 

Case XVIII. — John Baker, a child of five years old, was 
inoculated March 16, 1798, with matter taken from a pustule 
on the hand of Thomas Virgce, one of the servants who had 
been infected from the mare's heels. He became ill on the 
sixth day with symptoms similar to those excited by cow- 
pox matter. On the eighth day he was free from indispo- 
sition. 

There was some variation in the appearance of the pustule 
on the arm. Although it somewhat resembled a smallpox 
pustule, yet its similitude was not so conspicuous as when 
excited by matter from the nipple of the cow, or when the 
matter has passed from thence through the medium of the 
human subject 

This experiment was made to ascertain the progress and 
subsequent effects of the disease when thus propagated. We 
have seen that the virus from the horse, when it proves in- 
fectious to the human subject, is not to be relied upon as 
rendering the system secure from variolous infection, but 
that the matter produced by it upon the nipple of the cow is 
perfectly so. Whether its passing from the horse through 
the human constitution, as in the present instance, will pro- 
duce a similar effect, remains to be decided. This would 
how have been effected, but the boy was rendered unfit for 



VACCINATION AGAINST SMALLPOX 167 

inoculation from having felt the effects of a contagious fever 
in a workhouse soon after this experiment was made. 

Case XIX. — William Summers, a child of five years and 
a half old, was inoculated the same day with Baker, with 
matter taken from the nipples of one of the infected cows, 
at the farm alluded to. He became indisposed on the sixth 
day, vomited once, and felt the usual slight symptoms till 
the eighth day, when he appeared perfectly well. The prog- 
ress of the pustule, formed by the infection of the virus, was 
similar to that noticed in Case XVII, with this exception, 
its being free from the livid tint observed in that instance. 

Case XX. — From William Summers the disease was trans- 
ferred to William Pead, a boy of eight years old, who was 
inoculated March 28th. On the sixth day he complained of 
pain in the axilla, and on the seventh was affected with the 
common symptoms of a patient sickening with the smallpox 
from inoculation, which did not terminate till the third day 
after the seizure. So perfect was the similarity to the vari- 
olous fever that I was induced to examine the skin, con- 
ceiving there might have been some eruptions, but none 
appeared. The efflorescent blush around the part punctured 
in the boy's arm was so truly characteristic of that which 
appears on variolous inoculation that I have given a repre- 
sentation of it. The drawing was made when the pustule 
was beginning to die away and the areola retiring from the 
centre. 

Case XXL — A.pril 5th: Several children and adults were 
inoculated from the arm of William Pead. The greater part 
of them sickened on the sixth day, and were well on the 
seventh, but in three of the number a secondary indisposition 
arose in consequence of an extensive erysipelatous inflamma- 
tion which appeared on the inoculated arms. It seemed to 
arise from the state of the pustule, which spread out, accom- 
panied with some degree of pain, to about half the diameter 
of a sixpence. One of these patients was an infant of half 
a year old. By the application of mercurial ointment to the 
inflamed parts (a treatment recommended under similar cir- 



368 EDWARD JENNER 

cumstances in the inoculated smallpox) the complaint sub- 
sided without giving much trouble. 

Hannah Excell, an healthy girl of seven years old, and 
one of the patients above mentioned, received the infection 
from the insertion of the virus under the cuticle of the arm 
in three distinct points. The pustules which arose in con- 
sequence so much resembled, on the twelfth day, those 
appearing from the infection of variolous matter, that an 
experienced inoculator would scarcely have discovered a 
shade of difference at that period. Experience now tells me 
that almost the only variation which follows consists in the 
pustulous fluids remaining limpid nearly to the time of its 
total disappearance; and not, as in the direct smallpox, be- 
coming purulent. 

Case XXII. — From the arm of this girl matter was taken 
and inserted April 12th into the arms of John Macklove, one 
year and a half old, Robert F. Jenner, eleven months old, 
Mary Pead, five years old, and Mary James, six years old. 

Among these, Robert F. Jenner did not receive the in- 
fection. The arms of the other three inflamed properly and 
began to affect the system in the usual manner; but being 
under some apprehensions from the preceding cases that a 
troublesome erysipelas might arise, I determined on making 
an experiment with the view of cutting off its source. 
Accordingly, after the patients had felt an indisposition of 
about twelve hours, I applied in two of these cases out of 
the three, on the vesicle formed by the virus, a little mild 
caustic, composed of equal parts of quick-lime and soap, and 
suffered it to remain on the part six hours." It seemed to 
give the children but little uneasiness, and effectually answer- 
ed my intention in preventing the appearance of erysipelas. 
Indeed, it seemed to do more, for in half an hour after its 
application the indisposition of the children ceased." These 
precautions were perhaps unnecessary, as the arm of the 
third child, Mary Pead, which was suffered to take its com- 
mon course, scabbed quickly, without any erysipelas. 

11 Perhaps a few touches with the lapis septicus would have proved 
equally efficacious. 

" What effect would a similar treatment produce in inoculation for the 
smallpox? 



VACCINATION AGAINST SMALLPOX 169 

Case XXIII. — From this child's arm matter was taken 
and transferred to that of J. Barge, a boy of seven years old. 
He sickened on the eighth day, went through the disease 
with the usual slight symptoms, and without any inflamma- 
tion on the arm beyond the common efflorescence surround- 
ing the pustule, an appearance so often seen in inoculated 
smallpox. 

After the many fruitless attempts to give the smallpox to 
those who had had the cow-pox, it did not appear necessary, 
nor was it convenient to me, to inoculate the whole of those 
who had been the subjects of these late trials; yet I thought 
it right to see the effects of variolous matter on some of 
them, particularly William Summers, the first of these 
patients who had been infected with matter taken from the 
cow. He was, therefore, inoculated with variolous matter 
from a fresh pustule; but, as in the preceding cases, the 
system did not feel the effects of it in the smallest degree. 
I had an opportunity also of having this boy and William 
Pead inoculated by my nephew, Mr. Henry Jenner, whose 
report to me is as follows : " I have inoculated Pead and 
Barge, two of the boys whom you lately infected with the 
cow-pox. On the second day the incisions were inflamed and 
there was a pale inflammatory stain around them. On the 
third day these appearances were still increasing and their 
arms itched considerably. On the fourth day the inflam- 
mation was evidently subsiding, and on the sixth day it 
was scarcely perceptible. No symptom of indisposition 
followed. 

"To convince myself that the variolous matter made use 
of was in a perfect state I at the same time inoculated a 
patient with some of it who never had gone through the cow- 
pox, and it produced the smallpox in the usual regular man- 
ner." 

These experiments afforded me much satisfaction; they 
proved that the matter, in passing from one human subject to 
another, through five gradations, lost none of its original 
properties, J. Barge being the fifth who received the infection 
successively from William Summers, the boy to whom it was 
communicated from the cow. 



170 EDWARD JENNER 

I shall now conclude this inquiry with some general 
observations on the subject, and on some others which are 
interwoven with it. 

Although I presume it may be unnecessary to produce fur- 
ther testimony in support of my assertion "that the cow-pox 
protects the human constitution from the infection of the 
smallpox," yet it affords me considerable satisfaction to say 
that Lord Somerville, the President of the Board of Agricul- 
ture, to whom this paper was shewn by Sir Joseph Banks, 
has found upon inquiry that the ^ statements were confirmed 
by the concurring testimony of Mr. Dolland, a surgeon, who 
resides in a dairy country remote from this, in which these 
observations were made. With respect to the opinion ad- 
duced " that the source of the infection is u peculiar morbid 
matter arising in the horse," although I have not been able 
to prove it from actual experiments conducted immediately 
under my own eye, yet the evidence I have adduced appears 
sufficient to establish it. 

They who are not in the habit of conducting experiments 
may not be aware of the coincidence of circumstances neces- 
sary for their being managed so as to prove perfectly deci- 
sive ; nor how often men engaged in professional pursuits are 
liable to interruptions which disappoint them almost at the 
instant of their being accomplished: however, I feel no room 
for hesitation respecting the common origin of the disease, 
being well convinced that it never appears among the cows 
(except it can be traced to a cow introduced among the 
general herd which has been previously infected, or to an 
infected servant) unless they have been milked by some one 
who, at the same time, has the care of a horse affected with 
diseased heels. 

The spring of the year 1797, which I intended particularly 
to have devoted to the completion of this investigation, 
proved, from its dryness, remarkably adverse to my wishes; 
for it frequently happens, while the farmers' horses are ex- 
posed to the cold rains which fall at that season, that their 
heels become diseased, and no cow-pox then appeared in the 
neighbourhood. 

The active quality of the virus from the horses' heels is 
greatly increased after it has acted on the nipples of the 



VACCINATION AGAINST SMALLPOX 171 

cow, as it rarely happens that the horse affects his dresser 
with sores, and as rarely that a milkmaid escapes the infec- 
tion when she milks infected cows. It is most active at the 
commencement of the disease, even before it has acquired 
a pus-like appearance; indeed, I am not confident whether 
this property in the matter does not entirely cease as soon as 
it is secreted in the form of pus. I am induced to think it 
does cease, 13 and that it is the thin, darkish-locking fluid only, 
oozing from the newly-formed cracks in the heels, similar 
to what sometimes appears from erysipelatous blisters, which 
gives the disease. Nor am I certain that the nipples of the 
cows are at all times in a state to receive the infection. The 
appearance of the disease in the spring and the early part 
of the summer, when they are disposed to be affected with 
spontaneous eruptions so much more frequently than at 
other seasons, induces me to think that the virus from the 
horse must be received upon them when they are in this 
state, in order to produce effects : experiments, however, must 
determine these points. But it is clear that when the cow- 
pox virus is once generated, that the cows cannot resist the 
contagion, in whatever state their nipples may chance to be, 
if they are milked with an infected hand. 

Whether the matter, either from the cow or the horse, will 
affect the sound skin of the human body, I cannot positively 
determine; probably it will not, unless on those parts where 
the cuticle is extremely thin, as on the lips, for example. 1 
have known an instance of a poor girl who produced an 
ulceration on her lip by frequently holding her finger to her 
mouth to cool the raging of a cow-pox sore by blowing upon 
it. The hands of the farmers' servants here, from the nature 
of their employments, are constantly exposed to those in- 
juries which occasion abrasions of the cuticle, to punctures 
from thorns, and such like accidents ; so that they are always 
in a state to feel the consequence of exposure to infectious 
matter. 

It is singular to observe that the cow-pox virus, although 

18 It is very easy to procure pus from old sores on the heels of horses. 
This I have often inserted into scratches made with a lancet, on the 
sound nipples of cows, and have seen no other effects from it than simple 
inflammation. 



172 EDWARD JENNER 

it renders the constitution unsusceptible of the variolous, 
should nevertheless, leave it unchanged with respect 
to its own action. I have already produced an instance M 
to point out this, and shall now corroborate it with 
another. 

Elizabeth Wynne, who had the cow-pox in the year 1759, 
was inoculated with variolous matter, without effect, in the 
year 1797, and again caught the cow-pox in the year 1798. 
When I saw her, which was on the eighth day after she re- 
ceived the infection, I found her affected with general lassi- 
tude, shiverings, alternating with heat, coldness of the ex- 
tremities, and a quick and irregular pulse. These symptoms 
were preceded by a pain in the axilla. On her hand was 
one large pustulous sore, which resembled that delineated in 
Plate No. 1. (Plate appears in original.) 

It is curious also to observe that the virus, which with 
respect to its effects is undetermined and uncertain previously 
to its passing from the horse through the medium of the 
cow, should then not only become more active, but should 
invariably and completely possess those specific properties 
which induce in the human constitution symptoms similar to 
those of the variolous fever, and effect in it that peculiar 
change which for ever renders it unsusceptible of the vario- 
lous contagion. 

May it not then be reasonably conjectured that the source 
of the smallpox is morbid matter of a peculiar kind, gener- 
ated by a disease in the horse, and that accidental circum- 
stances may have again and again arisen, still working new 
changes upon it until it has acquired the contagious and 
malignant form under which we now commonly see it making 
its devastations amongst us? And, from a consideration of 
the change which the infectious matter undergoes from pro- 
ducing a disease on the cow, may we not conceive that many 
contagious diseases, now prevalent among us, may owe their 
present appearance not to a simple, but to a compound, ori- 
gin ? For example, is it difficult to imagine that the measles, 
the scarlet fever, and the ulcerous sore throat with a spotted 
skin have all sprung from the same source, assuming some 
variety in their forms according to the nature of their new 

" See Case IX. 



VACCINATION AGAINST SMALLPOX 173 

combinations? The same question will apply respecting the 
origin of many other contagious diseases which bear a 
strong analogy to each other. 

There are certainly more forms than one, without consid- 
ering the common variation between the confluent and dis- 
tinct, in which the smallpox appears in what is called the 
natural way. About seven years ago a species of smallpox 
spread through many of the towns and villages of this part 
of Gloucestershire: it was of so mild a nature that a fatal 
instance was scarcely ever heard of, and consequently so little 
dreaded by the lower orders of the community that they 
scrupled not to hold the same intercourse with each other as 
if no infectious disease had been present among them. I 
never saw nor heard of an instance of its being confluent. 
The most accurate manner, perhaps, in which I can convey 
an idea of it is by saying that had fifty individuals been taken 
promiscuously and infected by exposure to this contagion, 
they would have had as mild and light a disease as if they 
had been inoculated with variolous matter in the usual way. 
The harmless manner in which it shewed itself could not 
arise from any peculiarity either in the season or the weather, 
for I watched its progress upwards of a year without per- 
ceiving any variation in its general appearance. I consider 
it then as a variety of the smallpox. 15 

In some of the preceding cases I have noticed the atten- 
tion that was paid to the state of the variolous matter pre- 
vious to the experiment of inserting it into the arms of those 
who had gone through the cow-pox. This I conceived to be 
of great importance in conducting these experiments, and, 
were it always properly attended to by those who inoculate 
for the smallpox, it might prevent much subsequent mischief 
and confusion. With the view of enforcing so necessary 
a precaution I shall take the liberty of digressing so far as 
to point out some unpleasant facts relative to mismanage- 
ment in this particular, which have fallen under my own 
observation. 

15 My friend, Dr. Hicks, of Bristol, who, daring the prevalence of this 
distemper, was resident at Gloucester, and physician of the hospital there 
(where it was seen soon after its first appearance in this country), had 
opportunities of making numerous observations upon it, which it is his 
intention to communicate to the public. 



174 EDWARD JENNER 

A medical gentleman (now no more), who for many years 
inoculated in this neighbourhood, frequently preserved the 
variolous matter intended for his use on a piece of lint or 
cotton, which, in its fluid state, was put into a vial, corked, 
and conveyed into a warm pocket ; a situation certainly fa- 
vourable for speedily producing putrefaction in it. In this 
state (not unfrequently after it had been taken several days 
from the pustules) it was inserted into the arms of his 
patients, and brought on inflammation of the incised parts, 
swellings of the axillary glands, fever, and sometimes erup- 
tions. But what was this disease? Certainly not the small- 
pox; for the matter having from putrefaction lost or suf- 
fered a derangement in its specific properties, was no longer 
capable of producing that malady, those who had been inocu- 
lated in this manner being as much subject to the contagion 
of the smallpox as if they had never been under the influence 
of this artificial disease ; and many, unfortunately, fell vic- 
tims to it, who thought themselves in perfect security. The 
same unfortunate circumstance of giving a disease, supposed 
to be the smallpox, with inefficacious variolous matter, having 
occurred under the direction of some other practitioners 
within my knowledge, and probably from the same incautious 
method of securing the variolous matter, I avail myself of 
this opportunity of mentioning what I conceive to be of 
great importance; and, as a further cautionary hint, I shall 
again digress so far as to add another observation on the 
subject of inoculation. 

Whether it be yet ascertained by experiment that the 
quantity of variolous matter inserted into the skin makes any 
difference with respect to the subsequent mildness or violence 
of the disease, I know not; but I have the strongest reason 
for supposing that if either the punctures or incisions be 
made so deep as to go through it and wound the adipose mem- 
brane, that the risk of bringing on a violent disease is 
greatly increased. I have known an inoculator whose prac- 
tice was "to cut deep enough (to use his own expression) 
to see a bit of fat," and there to lodge the matter. The great 
number of bad cases, independent of inflammations and 
abscesses on the arms, and the fatality which attended this 
practice, was almost inconceivable; and I cannot account for 



VACCINATION AGAINST SMALLPOX 175 

it on any other principle than that of the matter being placed 
in this situation instead of the skin. 

It was the practice of another, whom I well remember, to 
pinch up a small portion of the skin on the arms of his pa- 
tients and to pass through it a needle, with a thread attached 
to it previously dipped in variolous matter. The thread was 
lodged in the perforated part, and consequently left in con- 
tact with the cellular membrane. This practice was attended 
with the same ill success as the former. Although it is very 
improbable that any one would now inoculate in this rude 
way by design, yet these observations may tend to place a 
double guard over the lancet, when infants, whose skins are 
comparatively so very thin, fall under the care of the 
inoculator. 

A very respectable friend of mine, Dr. Hardwicke, of Sod- 
bury, in this county, inoculated great numbers of patients 
previous to the introduction of the more modern method by 
Sutton, and with such success that a fatal instance occurred 
as rarely as since that method has been adopted. It was 
the doctor's practice to make as slight an incision as possible 
upon the skin, and there to lodge a thread saturated with 
the variolous matter. When his patients became indisposed, 
agreeably to the custom then prevailing, they were directed 
to go to bed and were kept moderately warm. Is it not 
probable then that the success of the modern practice may 
depend more upon the method of invariably depositing the 
virus in or upon the skin, than on the subsequent treatment 
of the disease? 

I do not mean to insinuate that exposure to cool air, and 
suffering the patient to drink cold water when hot and thirsty, 
may not moderate the eruptive symptoms and lessen the num- 
ber of pustules; yet, to repeat my former observation, I 
cannot account for the uninterrupted success, or nearly so, 
of one practitioner, and the wretched state of the patients 
under the care of another, where, in both instances, the gen- 
eral treatment did not differ essentially, without conceiving 
it to arise from the different modes of inserting the matter 
for the purpose of producing the disease. As it is not the 
identical matter inserted which is absorbed into the constitu- 
tion, but that which is, by some peculiar process in the animal 



176 EDWARD JENNER 

economy, generated by it, is it not probable that different 
parts of the human body may prepare or modify the virus 
differently? Although the skin, for example, adipose mem- 
brane, or mucous membranes are all capable of producing 
the variolous virus by the stimulus given by the particles 
originally deposited upon them, yet I am induced to conceive 
that each of these parts is capable of producing some vari- 
ation in the qualities of the matter previous to its affecting 
the constitution. What else can constitute the difference be- 
tween the smallpox when communicated casually or in what 
has been termed the natural way, or when brought on arti- 
ficially through the medium of the skin? 

After all, are the variolous particles, possessing their true 
specific and contagious principles, ever taken up and con- 
veyed I y the lymphatics unchanged into the blood vessels? I 
imagine not. Were this the case, should we not find the blood 
sufficiently loaded with them in some stages of the smallpox 
to communicate the disease by inserting it under the cuticle, 
or by spreading it on the surface of an ulcer? Yet experi- 
ments have determined the impracticability of its being given 
in this way; although it has been proved that variolous 
matter, when much diluted with water and applied to the 
skin in the usual manner, will produce the disease. But it 
would be digressing beyond a proper boundary to go minutely 
into this subject here. 

At what period the cow-pox was first noticed here is not 
upon record. Our oldest farmers were not unacquainted with 
it in their earliest days, when it appeared among their farms 
without any deviation from the phaenomena which it now ex- 
hibits. Its connection with the smallpox seems to have been 
unknown to them. Probably the general introduction of 
inoculation first occasioned the discovery. 

Its rise in this country may not have been of very remote 
date, as the practice of milking cows might formerly have 
been in the hands of women only; which I believe is the case 
now in some other dairy countries, and, consequently, that 
the cows might not in former times have been exposed to the 
contagious matter brought by the men servants from the 
heels of horses. 1 * Indeed, a knowledge of the source of the 

**I have been informed from respectable authority that in Ireland, al- 



VACCINATION AGAINST SMALLPOX 177 

infection is new in the minds of most of the farmers in this 
neighbourhood, but it has at length produced good conse- 
quences; and it seems probable, from the precautions they 
are now disposed to adopt, that the appearance of the cow- 
pox here may either be entirely extinguished or become ex- 
tremely rare. 

Should it be asked whether this investigation is a matter 
of mere curiosity, or whether it tends to any beneficial pur- 
pose, I should answer that, notwithstanding the happy effects 
of inoculation, with all the improvements which the practice 
has received since its first introduction into this country, it 
not very unfrequently produces deformity of the skin, and 
sometimes, under the best management, proves fatal. 

These circumstances must naturally create in every in- 
stance some degree of painful solicitude for its consequences. 
But as I have never known fatal effects arise from the cow- 
pox, even when impressed in the most unfavourable manner, 
producing extensive inflammations and suppurations on the 
hands; and as it clearly appears that this disease leaves the 
constitution in a state of perfect security from the infection 
of the smallpox, may we not infer that a mode of inoculation 
may be introduced preferable to that at present adopted, 
especially among those families which, from previous cir- 
cumstances, we may judge to be predisposed to have the dis- 
ease unfavourably? It is an excess in the number of pustules 
which we chiefly dread in the smallpox; but in the cow-pox 
no pustules appear, nor does it seem possible for the con- 
tagious matter to produce the disease from effluvia, or by any 
other means than contact, and that probably not simply be- 
tween the virus and the cuticle; so that a single individual 
in a family might at any time receive it without the risk 
of infecting the rest or of spreading a distemper that fills a 
country with terror. 

Several instances have come under my observation which 
justify the assertion that the disease cannot be propagated by 
effluvia. The first boy whom I inoculated with the matter 

though dairies abound in many parts of the island, the disease is entirely 
unknown. Ths reason seems obvious. The business of the dairy is con- 
ducted by women only. Were the meanest vassal among the men employed 
there as a milker at a dairy, he would feel his situation unpleasant beyond 
all endurance* 



178 EDWARD JENNER 

of cow-pox slept in a bed, while the experiment was going 
forward, with two children who never had gone through 
either that disease or the smallpox, without infecting either 
of them. 

A young woman who had the cow-pox to a great extent, 
several sores which maturated having appeared on the hands 
and wrists, slept in the same bed with a fellow-dairymaid 
who never had been infected with either the cow-pox or the 
smallpox, but no indisposition followed. 

Another instance has occurred of a young woman on whose 
hands were several large suppurations from the cow-pox, 
who was at the same time a daily nurse to an infant, but the 
complaint was not communicated to the child. 

In some other points of view the inoculation of this disease 
appears preferable to the variolous inoculation. 

In constitutions predisposed to scrophula, how frequently 
we see the inoculated smallpox rouse into activity that dis- 
tressful malady! This circumstance does not seem to de- 
pend on the manner in which the distemper has shewn it- 
self, for it has as frequently happened among those who have 
had it mildly as when it has appeared in the contrary way. 

There are many who, from some peculiarity in the habit, re- 
sist the common effects of variolous matter inserted into the 
skin, and who are in consequence haunted through life with 
the distressing idea of being insecure from subsequent in- 
fection. A ready mode of dissipating anxiety originating 
from such a cause must now appear obvious. And, as we 
have seen that the constitution may at any time be made to 
feel the febrile attack of cow-pox, might it not, in many 
chronic diseases, be introduced into the system, with the 
probability of affording relief, upon well-known physiological 
principles? 

Although I say the system may at any time be made to 
feel the febrile attack of cow-pox, yet I have a single instance 
before me where the virus acted locally only, but it is not in 
the least probable that the same person would resist the action 
both of the cow-pox virus and the variolous. 

Elizabeth Sarfenet lived as a dairymaid at Newpark farm, 
in this parish. All the cows and the servants employed in 
milking had the cow-pox; but this woman, though she had 



VACCINATION AGAINST SMALLPOX 179 

several sores upon her fingers, felt no tumours in the axilla, 
nor any general indisposition. On being afterwards casually 
exposed to variolous infection, she had the smallpox in a 
mild way. Hannah Pick, another of the dairymaids who was 
a fellow-servant with Elizabeth Sarfenet when the dis- 
temper broke out at the farm, was, at the same time, in- 
fected; but this young woman had not only sores upon her 
hands, but felt herself also much indisposed for a day or 
two. After this, I made several attempts to give her the 
smallpox by inoculation, but they all proved fruitless. From 
the former case then we see that the animal economy is 
subject to the same laws in one disease as the other. 

The following case, which has very lately occurred, renders 
it highly probable that not only the heels of the horse, but 
other parts of the body of that animal, are capable of generat 
ing the virus which produces the cow-pox. 

An extensive inflammation of the erysipelatous kind ap- 
peared without any apparent cause upon the upper part of 
the thigh of a sucking colt, the property of Mr. Millet, a 
farmer at Rockhampton, a village near Berkeley. The in- 
flammation continued several weeks, and at length terminated 
in the formation of three or four small abscesses. The 
inflamed parts were fomented, and dressings were applied by 
some of the same persons who were employed in milking 
the cows. The number of cows milked was twenty- four, and 
the whole of them had the cow-pox. The milkers, consist- 
ing of the farmer's wife, a man and a maidservant, were 
infected by the cows. The man-servant had previously gone 
through the smallpox, and felt but little of the cow-pox. 
The servant maid had some years before been infected with 
the cow-pox, and she also felt it now in a slight degree; but 
the farmer's wife, who never had gone through either of the 
diseases, felt its effects very severely. 

That the disease produced upon the cows by the colt and 
from thence conveyed to those who milked them was the true 
and not the spurious cow-pox, there can be scarcely any. 
room for suspicion; yet it would have been more completely 
satisfactory had the effects of variolous matter been ascer- 
tained on the farmer's wife, but there was a peculiarity in 
her situation which prevented my making the experiment. 



180 EDWARD JENNER 

Thus far have I proceeded in an inquiry founded, as it 
must appear, on the basis of experiment; in which, however, 
conjecture has been occasionally admitted in order to present 
to persons well situated for such discussions objects for a 
more minute investigation. In the mean time I shall myself 
continue to prosecute this inquiry, encouraged by the hope 
of its becoming essentially beneficial to mankind. 



II 

Further Observations on the Variola Vaccinae, or 
Cow-pox. 1799 

Although it has not been in my power to extend the in- 
quiry into the causes and effects of the variolar vaccinae much 
beyond its original limits, yet, perceiving that it is begin- 
ning to excite a general spirit of investigation, I think it of 
importance, without delay, to communicate such facts as 
have since occurred, and to point out the fallacious sources 
from whence a disease imitative of the true variolas vac- 
cinae might arise, with the view of preventing those who 
may inoculate from producing a spurious disease; and, 
further, to enforce the precaution suggested in the former 
treatise on the subject, of subduing the inoculated pustule as 
soon as it has sufficiently produced its influence on the con- 
stitution. From a want of due discrimination of the real ex- 
istence of the disease, either in the brute or in the human 
subject, and also of that stage of it in which it is capable of 
producing the change in the animal economy which renders 
it unsusceptible of the contagion of the smallpox, unpleasant 
consequences might ensue, the source of which, perhaps, 
might not be suspected by one inexperienced in conducting 
such experiments. 

My late publication contains a relation of most of the 
facts which had come under my own inspection at the time 
it was written, interspersed with some conjectural observa- 
tions. Since then Dr. G. Pearson has established an inquiry 
into the validity of my principal assertion, the result of which 
cannot but be highly flattering to my feelings. It contains not 



VACCINATION AGAINST SMALLPOX 181 

a single case which I think can be called an exception to 
the fact I was so firmly impressed with — that the cow-pox 
protects the human body from the smallpox. I have myself 
received some further confirmations, which shall be subjoined. 
I have lately also been favoured with a letter from a gentle- 
man of great respectability (Dr. Ingenhousz), informing me 
that, on making an inquiry into the subject in the county of 
Wilts, he discovered that a farmer near Calne had been in- 
fected with the smallpox after having had the cow-pox, and 
that the disease in each instance was so strongly characterized 
as to render the facts incontrovertible. The cow-pox, it 
seems, from the doctor's information, was communicated to 
the farmer from his cows at the time that they gave out an 
offensive stench from their udders. 

Some other instances have likewise been represented to 
me of the appearance of the disease, apparently marked with 
its characteristic symptoms, and yet that the patients have 
afterwards had the smallpox. On these cases I shall, for 
the present, suspend any particular remarks, but hope that 
the gexieral observations I have to offer in the sequel will 
prove of sufficient weight to render the idea of their ever 
having had existence, but as cases of spurious cow-pox, 
extremely doubtful. 

Ere I proceed let me be permitted to observe that truth, 
in this and every other physiological inquiry that has occu- 
pied my attention, has ever been the object of my pursuit, 
and should it appear in the present instance that I have been 
led into error, fond as I may appear of the offspring of my 
labours, I had rather see it perish at once than exist and do a 
public injury. 

I shall proceed to enumerate the sources, or what appear 
to me as such, of a spurious cow-pox. 

First : That arising from pustules on the nipples or udder of 
the cow; which pustules contain no specific virus. 

Secondly: From matter (although originally possessing the 
specific virus) which has suffered a decomposition, either 
from putrefaction or from any other cause less obvious to 
the senses. 

Thirdly : From matter taken from an ulcer in an advanced 
stage, which ulcer arose from a true cow pock. 



182 EDWARD JENNER 

. Fourthly: From matter produced on the human skin from 
contact with some peculiar morbid matter generated by a 
horse, ■ 

On these subjects I shall offer some comments: First, 
to what length pustulous diseases of the udder and nipples 
of the cow may extend it is not in my power to determine; 
but certain it is that these parts of the animal are subject to 
some variety of maladies of this nature; and as many of 
these eruptions (probably all of them) are capable of giving 
a disease to the human body, would it not be discreet for 
those engaged in this investigation to suspend controversy 
and cavil until they can ascertain with precision what is and 
what is not the cow-pox ? 

For example: A farmer who is not conversant with any 
of these maladies, but who may have heard of the cow-pox 
in general terms, may acquaint a neighbouring surgeon that 
the distemper appears at his farm. The surgeon, eager to 
make an experiment, takes away matter, inoculates, produces 
a sore, uneasiness in the axilla, and perhaps some affection 
of the system. This is one way in which a fallacious idea 
of security both in the mind of the inoculator and the patient 
may arise; for a disease may thus have been propagated from 
a simple eruption only. 

One of the first objects then of this pursuit, as I have 
observed, should be, to learn how to distinguish with ac- 
curacy between that peculiar pustule which is the true cow 
pock, and that which is spurious. Until experience has de- 
termined this, we view our object through a mist. Let us, 
for instance, suppose that the smallpox and the chicken-pox 
were at the same time to spread among the inhabitants of a 
country which had never been visited by either of these dis- 
tempers, and where they were quite unknown before: what 
confusion would arise ! The resemblance between the symp- 
toms of the eruptive fever and between the pustules in either 
case would be so striking that a patient who had gone through 
the chicken-pox to any extent would feel equally easy with 
regard to his future security from the smallpox as the person 
who had actually passed through that disease. Time and 
future observation would draw the line of distinction. 

So I presume it will be with the cow-pox until it is more 



VACCINATION AGAINST SMALLPOX 183 

generally understood. All cavilling, therefore, on the mere 
report of those who tell us they have had this distemper, and 
are afterwards found susceptible of the smallpox, should be 
suspended. To illustrate this I beg leave to give the fol- 
lowing history: 

Sarah Merlin, of the parish of Eastington in this county, 
when about thirteen or fourteen years of age lived as a ser- 
vant with farmer Clarke, who kept a dairy consisting of about 
eighteen cows at Stonehouse, a neighbouring village. The 
nipples and udders of three of the cows were extensively af- 
fected with large white blisters. These cows the girl milked 
daily, and at the time she assisted, with two others, in milk- 
ing the rest of the herd. It soon appeared that the disease 
was communicated to the girl. The rest of the cows escaped 
the infection, although they were milked several days after 
the three above specified, had these eruptions on the nipples 
and udders, and even after the girl's hand became sore. The 
two others who were engaged in milking, although they 
milked the cows indiscriminately, received no injury. On 
the fingers of each of the girl's hands there appeared several 
large white blisters — she supposes about three or four on each 
finger. The hands and arms inflamed and swelled, but no 
constitutional indisposition followed. The sores were 
anointed with some domestic ointment and got well without 
ulcerating. 

As this malady was called the cow-pox, and recorded as 
such in the mind of the patient, she became regardless of 
the smallpox; but, on being exposed to it some years after- 
wards she was infected, and had a full burthen. 

Now had any one conversant with the habits of the dis- 
ease heard this history, they would have had no hesitation 
in pronouncing it a case of spurious cow-pox; considering 
its deviation in the numerous blisters which appeared on the 
girl's hands; their termination without ulceration; its not 
proving more generally contagious at the farm, either among 
the cattle or those employed in milking ; and considering also 
that the patient felt no general indisposition, although there 
was so great a number of vesicles. 

This is perhaps the most deceptious form in which an 
eruptive disease can be communicated from the cow, and it 



184 EDWARD JENNEB 

certainly requires some attention in discriminating it The 
most perfect criterion by which the judgment may be guided 
is perhaps that adopted by those who attend infected cattle. 
These white blisters on the nipples, they say, never eat into 
the fleshy parts like those which are commonly of a bluish 
cast, and which constitute the true cow-pox, but that they 
affect the skin only, quickly end in scabs, and are not nearly 
so infectious. 

That which appeared to me as one cause of spurious erup- 
tions, I have already remarked in the former treatise, name- 
ly, the transition that the cow makes in the spring from a 
poor to a nutritious diet, and from the udder's becoming at 
this time more vascular than usual for the supply of milk. 
But there is another source of inflammation and pustules 
which I believe is not uncommon in all the dairy counties in 
the west of England. A cow intended to be exposed for sale, 
having naturally a small udder, is previously for a day or 
two neither milked artificially nor is her calf suffered to have 
access to her. Thus the milk is preternaturally accumulated, 
and the udder and nipples become greatly distended. The 
consequences frequently are inflammation and eruptions 
which maturate. 

Whether a disease generated in this way has the power of 
affecting the constitution in any peculiar manner I cannot 
presume positively to determine. It has been conjectured to 
have been a cause of the true cow-pox, though my inquiries 
have not led me to adopt this supposition in any one in- 
stance; on the contrary, I have known the milkers affected 
by it, but always found that an affection thus induced left the 
system as susceptible of the smallpox as before. 

What is advanced in my second position I consider also of 
very great importance, and I could wish it to be strongly im- 
pressed on the minds of all who may be disposed to conclude 
hastily on my observations, whether engaged in their inves- 
tigation by experiments or not. To place this in its clearest 
point of view (as the similarity between the action of the 
smallpox and the cow-pox matter is so obvious) it will be 
necessary to consider what we sometimes observe to take 
place in inoculation for the smallpox when imperfect vario- 
lous matter is made use of. The concise history on this sub- 



VACCINATION AGAINST SMALLPOX 185 

Ject that was brought forward respecting what I had observed 
in this neighbourhood 1 I perceive, by a reference since made 
to the Memoirs of the Medical Society of London, may be 
considered as no more than a corroboration of the facts very 
clearly detailed by Mr. Kite. 2 To this copious evidence I have 
to add still more in the following communications from Mr. 
Earle, surgeon, of Frampton-upon-Severn, in this county, 
which I deem the more valuable, as he has with much candour 
permitted me to make them public: 

"Sir: 

" I have read with satisfaction your late publication on the 
Variolae Vaccina?, and being, among many other curious cir- 
cumstances, particularly struck with that relating to the in- 
efficacy of smallpox matter in a particular state, I think it 
proper to lay before you the following facts which came 
within my own knowledge, and which certainly tend to 
strengthen the opinions advanced in pages 56 and 57 of 
your treatise. 

"In March, 1784, a general inoculation took place at 
Arlingham in this county. I inoculated several patients with 
active variolous matter, all of whom had the disease in a 
favourable way ; but the matter being all used, and not being 
able to procure any more in the state I wished, I was under 
the necessity of taking it from a pustule which, experience 
has since proved, was advanced too far to answer the pur- 
pose I intended. Of five persons inoculated with this last 
matter, four took the smallpox afterwards in the natural 
way, one of whom died, three recovered, and the other, being 
cautioned by me to avoid as much as possible the chance of 
catching it, escaped from the disease through life. He died 
of another disorder about two years ago. 

"Although one of these cases ended unfortunate, yet I 
cannot suppose that any medical man will think me careless 
or inattentive in their management; for I conceive the ap- 
pearances were such as might have induced any one to sup- 

* Inquiry into the Causes and Effects of the Variolic Vaccinae, p. 56 of the 
original article. 

2 See an account of some anomalous appearances consequent to the inocu- 
lation of the smallpox, by Charles Kite, Surgeon, of Gravesend, in the 
Memoirs of the Medical Society of London, vol. iv, p. 114. 



186 EDWARD JENNER 

pose that the persons were perfectly safe from future in- 
fection. Inflammation in every case took place in the arm, 
and fever came on with a considerable degree of pain in the 
axilla. In some of their arms the inflammation and suppura- 
tion were more violent than is commonly observed when per- 
fect matter is made use of ; in one there was an ulcer which 
cast off several large sloughs. About the ninth day eruptions 
appeared, which died away earlier than common without ma- 
turation. From these circumstances I should suppose that no 
medical practitioner would scarcely have entertained a doubt 
but that these patients had been infected with a true small- 
pox; yet I must confess that some small degree of doubt pre- 
sented itself to me at the speedy disappearance of the erup- 
tions; and in order, as far as I could, to ascertain their 
safety, I sent one of them to a much older practitioner than 
myself. This gentleman, on hearing the circumstances of 
the case, pronounced the patient perfectly secure from future 
infection. 

" The following facts are also a striking proof of the 
truth of your observations on this subject: 

" In the year 1789 I inoculated three children of Mr. 
Coaley, of Hurst farm in this county. The arms inflamed 
properly, fever and pain in the axillae came on precisely 
the same as in the former cases, and in ten days eruptions 
appeared, which disappeared in the course of two days. I 
must observe that the matter here made use of was pro- 
cured for me by a friend; but no doubt it was in an im- 
proper state; for, from the similarity of these cases to those 
which happened at Arlingham five years before, I was some- 
what alarmed for their safety, and desired to inoculate them 
again: which being permitted, I was particularly careful to 
procure matter in its most perfect state. All the children 
took the smallpox from this second inoculation, and all 
had a very full burthen. These facts I conceive strikingly 
corroborate your opinion relative to the different states 
of matter; for in both instances that I have mentioned it 
was capable of producing something strongly resembling 
the true smallpox, although it afterwards proved not to 
be so. 

"As I think the communication of these cases is a duty 



VACCINATION AGAINST SMALLPOX 187 

I owe to the public, you are at liberty to make what use 
you please of this letter. I remain, &c, 

"John Earle. 

" Frampton-upon Severn, Gloucestershire, November 10, 1798. 

" P. S. I think it necessary to observe that I can pro- 
nounce, with the greatest certainty, that the matter with 
which the Arlingham patients were inoculated was taken 
from a true smallpox pustule. I took it myself from a 
subject that had a very full burthen." 

Certain then it is that variolous matter may undergo such 
a change from the putrefactive process, as well as from 
some of the more obscure and latent processes of nature, 
as will render it incapable of giving the smallpox in such 
a manner as to secure the human constitution from future 
infection, although we see at the same time it is capable 
of exciting a disease which bears so strong a resemblance 
to it as to produce inflammation and matter in the incised 
skin (frequently, indeed, more violent than when it pro- 
duces its effects perfectly), swelling of the axillary glands, 
general indisposition, and eruptions. So strongly persuaded 
was the gentleman, whose practice I have mentioned in page 
56 of the late treatise, that he could produce a mild small- 
pox by his mode of managing the matter, that he spoke of 
it as a useful discovery until convinced of his error by the 
fatal consequence which ensued. 

After this ought we to be in the smallest degree surprised 
to find, among a great number of individuals who, by living 
in dairies, have been casually exposed to the cow-pox virus 
when in a state analogous to that of the smallpox above de- 
scribed, some who may have had the disease so imperfectly 
as not to render them secure from variolous attacks? For 
the matter, when burst from the pustules on the nipples of 
the cow, by being exposed, from its lodgment there, to the 
heat of an inflamed surface, and from being at the same 
time in a situation to be occasionally moistened with milk, 
is often likely to be in a state conducive to putrefaction; 
and thus, under some modification of decomposition, it must, 
of course, sometimes find access to the hand o£ the milker 



188 EDWARD JENNER 

in such a way as to infect him. What confusion should we 
have were there no other mode of inoculating the smallpox 
than such as would happen from handling the diseased skin 
of a person labouring under that distemper in some of its 
advanced and loathsome stages I It must be observed that 
every case of cow-pox in the human species, whether com- 
municated by design or otherwise, is to be considered as a 
case of inoculation. And here I may be allowed to make 
an observation on the case of the farmer communicated to 
me by Dr. Ingenhousz. That he was exposed to the matter 
when it had undergone the putrefactive change is highly 
probable from the doctor's observing that the sick cows at 
the farm gave out an offensive stench from their udders. 
However, I must remark that it is unusual for cattle to 
suffer to such an extent, when disordered with the cow- 
pox, as to make a bystander sensible of any ill smell. I 
have often stood among a herd which had the distemper 
without being conscious of its presence from any particular 
effluvia. Indeed, in this neighbourhood it commonly re- 
ceives an early check from escharotic applications of the 
cow leech. It has been conceived to be contagious with- 
out contact; but this idea cannot be well founded because 
the cattle in one meadow do not infect those in another 
(although there may be no other partition than a hedge) 
unless they be handled or milked by those who bring the 
infectious matter with them; and of course, the smallest 
particle imaginable, when applied to a part susceptible of 
its influence, may produce the effect. Among the human 
species it appears to be very clear that the disease is pro- 
duced by contact only. All my attempts, at least, to com- 
municate it by effluvia have hitherto proved ineffectual. 

As well as the perfect change from that state in which 
variolous matter is capable of producing full and decisive 
effects on the constitution, to that wherein its specific prop- 
erties are entirely lost, it may reasonably be supposed that 
it is capable of undergoing a variety of intermediate 
changes. The following singular occurrences in ten cases 
of inoculation, obligingly communicated to me by Mr. Trye, 
Senior Surgeon to the Infirmary at Giocester, seem to indi- 
cate that the variolous matter, previously to its being takes 



VACCINATION AGAINST SMALLPOX 189 

from the patient for the intended purpose, was beginning 
to part with some of its original properties, or, in other 
words, that it had suffered a partial decomposition. Mr. 
Trye says : " I inoculated ten children with matter taken at 
one time and from the same subject. I observed no pecu- 
liarity in any of them previously to their inoculation, nor 
did any thing remarkable appear in their arms till after 
the decline of the disease. Two infants of three months old 
had erysipelas about the incisions, in one of them extending 
from the shoulders to the fingers' ends. Another infant 
had abscesses in the cellular substance in the neighbour- 
hood of the incisions, and five or six of the rest had axillary 
abscesses. The matter was taken from the distinct small- 
pox late in its progress, and when some pustules had been 
dried. It was received upon glass and slowly dried by the 
fire. All the children had pustules which maturated, so 
that I suppose them all secure from future infection; at 
least, as secure as any others whom I have ever inoculated. 
My practice never afforded a sore arm before." 

In regard to my former observation on the improper and 
dangerous mode of preserving variolous matter, I shall here 
remark that it seems not to have been clearly understood. 
Finding that it has been confounded with the more eligible 
modes of preservation, I will explain myself further. When 
the matter is taken from a fit pustule and properly prepared 
for preservation, it may certainly be kept without losing its 
specific properties a great length of time ; for instance, when 
it is previously dried in the open air on some compact body, 
as a quill or a piece of glass, and afterwards secured in a 
small vial. 8 But when kept several days in a state of mois- 
ture, and during that time exposed to a warm temperature, 
I do not think it can be relied upon as capable of giving a 
perfect disease, although, as I have before observed, the 
progress of the symptoms arising from the action of the 
imperfect matter bear so strong a resemblance to the small- 
pox when excited completely. 

Thirdly. That the first formed virus, or what constitutes 
the true cow-pox pustule, invariably possesses the power I 

* Thus prepared, the cow-pox virus was found perfectly active, atid pos» 
sessing all its specific properties, at the end of three months. 



190 EDWARD JENNER 

have ascribed to it, namely, that of affecting the constitution 
with a specific disease, is a truth that no subsequent occur- 
rence has yet led me to doubt. But as I am now endeavour- 
ing to guard the public as much as possible against erroneous 
conclusions, I shall observe that when this pustule has de- 
generated into an ulcer (to which state it is often disposed 
to pass unless timely checked), I suspect that matter possess- 
ing very different properties may sooner or later be pro- 
duced; and although it may have passed that stage wherein 
the specific properties of the matter secreted are no longer 
present in it, yet when applied to a sore (as in the casual 
way) it might dispose that sore to ulcerate, and from its 
irritation the system would probably become affected; and 
thus, by assuming some of its strongest characters, it 
would imitate the genuine cow-pox. 

From the preceding observations on the matter of small- 
pox when decomposed it must, I conceive, be admitted that 
cow-pox matter in the state now described may produce 
a disease, the effects of which may be felt both locally and 
generally, yet that the disease thus induced may not be ef- 
fectual in obviating the future effects of variolous con- 
tagion. In the case of Mary Miller, related by Mr. Kite 
in the volume above alluded to, it appears that the inflam- 
mation and suppuration of the inoculated arm were more 
than usually severe, although the system underwent no 
specific change from the action of the virus; which ap- 
pears from the patient's sickening seven weeks afterwards 
with the natural smallpox, which went through its course. 
Some of the cases communicated by Mr. Earle tend further 
to confirm this fact, as the matter there manifestly pro- 
duced ulceration on the inoculated part to a considerable 
extent. 

Fourthly. Whether the cow-pox is a spontaneous disease 
in the cow, or is to be attributed to matter conveyed to the 
animal, as I have conceived, from the horse, is a question 
which, though I shall not attempt now fully to discuss, yet 
I shall digress so far as to adduce some further observa- 
tions, and to give my reasons more at large for taking up 
an opinion that to some had appeared fanciful. The ag- 
gregate of these observations, though not amounting to 



VACCINATION AGAINST SMALLPOX 191 

positive proof, forms presumptive evidence of so forcible 
a kind that I imagine it might, on any other person, have 
made the same impression it did on me, without fixing the 
imputation of credulity. 

First: I conceived this was the source, from observing 
that where the cow-pox had appeared among the dairies 
here (unless it could be traced to the introduction of an 
infected cow or servant) it had been preceded at the farm 
by a horse diseased in the manner already described, which 
horse had been attended by some of the milkers. 

Secondly: From its being a popular opinion throughout 
this great dairy country, and from its being insisted on by 
those who here attend sick cattle. 

Thirdly: From the total absence of the disease in Ireland 
and Scotland, where the men-servants are not employed 
in the dairies.* 

Fourthly: From having observed that morbid matter gen- 
erated by the horse frequently communicates, in a casual 
way, a disease to the human subject so like the cow-pox 
that, in many cases, it would be difficult to make the dis- 
tinction between one and the other. 5 

Fifthly: From being induced to suppose, from experi- 
ments, that some of those who had been thus affected from 
the horse resisted the smallpox. 

Sixthly: From the progress and general appearance of 
the pustule on the arm of the boy whom I inoculated with 
matter taken from the hand of a man infected by a horse; 
and from the similarity to the cow-pox of general consti- 
tutional symptoms which followed. 6 

I fear it would be trespassing too far to adduce the gen- 
eral testimony of our farmers in support of this opinion; 
yet I beg leave to introduce an extract of a letter on this 

* This information was communicated to me from the first authority. 

6 The sound skin does not appear to be susceptible of this virus when 
inserted into it, but, when previously diseased from little accidents, its 
effects are often conspicuous. 

6 This case (on which I laid no inconsiderable stress in my late treatise, 
as presumptive evidence of the fact adduced) seems to have been either 
mistaken or overlooked by those who have commented upon it. (See Case 
XVIII, p. 36.) The boy, unfortunately, died of a fever at a parish work- 
house before I had an opportunity of observing what effects would have 
been produced by the matter of smallpox. 



192 EDWARD JENNER 

subject from the Rev. Mr. Moore, of Chalford Hill, in this 
county : 

"In the month of November, 1797, my horse had dis- 
eased heels, which was certainly what is termed the grease; 
and at a short subsequent period my cow was also affected 
with what a neighbouring farmer (who was conversant with 
the complaints of cattle) pronounced to be the cow-pox, 
which he at the same time observed my servant would be 
infected with: and this proved to be the case; for he had 
eruptions on his hands, face, and many parts of the body, 
the pustules appearing large, and not much like the small- 
pox, for which he had been inoculated a year and a half 
before, and had then a very heavy burthen. The pustules 
on the face might arise from contact with his hands, as he 
had a habit of rubbing his forehead, where the sores were 
the largest and the thickest 

" The boy associated with the farmer's sons during the 
continuance of the disease, neither of whom had had the 
smallpox, but they felt no ill effects whatever. He was 
not much indisposed, as the disease did not prevent him 
from following his occupations as usual. No other person 
attended the horse or milked the cow but the lad above 
mentioned. I am firmly of opinion that the disease in the 
heels of the horse, which was a virulent grease, was the 
origin of the servant's and the cow's malady." 

But to return to the more immediate object of this propo- 
sition. 

From the similarity of symptoms, both constitutional and 
local, between the cow-pox and the disease received from 
morbid matter generated by a horse, the common people in 
this neighbourhood, when infected with this disease, through 
a strange perversion of terms, frequently call it the cow-pox. 
Let us suppose, then, such a malady to appear among some 
of the servants at a farm, and at the same time that the 
cow-pox were to break out among the cattle; and let us 
suppose, too, that some of the servants were infected in 
this way, and that others received the infection from the 
cows. It would be recorded at the farm, and among the 
servants themselves wherever they might afterwards be 
dispersed, that they had all had the cow-pox. But it is 



VACCINATION AGAINST SMALLPOX 193 

clear that an individual thus infected from the horse would 
neither be for a certainty secure himself, nor would he im- 
part security to others were they inoculated by virus thus 
generated. He still would be in danger of taking the small- 
pox. Yet were this to happen before the nature of the cow- 
pox be more maturely considered by the public my evi- 
dence on the subject might be depreciated unjustly. For 
an exemplification of what is here advanced relative to the 
nature of the infection when received directly from the 
horse see Inquiry into the Causes and Effects of the 
Variolas Vaccinae, pp. 27, 28, 29, 30, and p. 35; and by way 
of further example, I beg leave to subjoin the following in- 
telligence received from Mr. Fewster, Surgeon, of Thorn- 
bury, in this county, a gentleman perfectly well acquainted 
with the appearances of the cow-pox on the human subject: 
" William Morris, aged thirty-two, servant to Mr. Cox of 
Almondsbury, in this county, applied to me the 2d of April, 
1798. He told me that, four days before, he found a stiff- 
ness and swelling in both his hands, which were so painful 
it was with difficulty he continued his work; that he had 
been seized with pain in his head, small of the back, and 
limbs, and with frequent chilly fits succeeded by fever. On 
examination I found him still affected with these symptoms, 
and that there was a great prostration of strength. Many 
parts of his hands on the inside were chapped, and on the 
middle joint of the thumb of the right hand there was a 
small phagedenic ulcer, about the size of a large pea, dis- 
charging an ichorous fluid. On the middle finger of the 
same hand there was another ulcer of a similar kind. These 
sores were of a circular form, and he described their first 
appearance as being somewhat like blisters arising from a 
burn. He complained of excessive pain, which extended 
up his arm into the axilla. These symptoms and appear- 
ances of the sores were so exactly like the cow-pox that I 
pronounced he had taken the distemper from milking cows. 
He assured me he had not milked a cow for more than half 
a year, and that his master's cows had nothing the matter 
with them. I then asked him if his master had a greasy 
horse, which he answered in the affirmative, and further said 
that he had constantly dressed him twice a day for the 

(7) HC — Vol. 33 



194 EDWARD JENNER 

last three weeks or more, and remarked that the smell of 
his hands was much like that of the horses's heels. On the 
5th of April I again saw him, and found him still complain- 
ing of pain in both hands, nor were his febrile symptoms 
at all relieved. The ulcers had now spread to the size of 
a seven-shilling gold coin, and another ulcer, which I had 
not noticed before, appeared on the first joint of the fore- 
finger of the left hand, equally painful with that on the 
right. I ordered him to bathe his hands in warm bran and 
water, applied escharotics to the ulcers, and wrapped his 
hands up in a soft cataplasm. The next day he was much 
relieved, and in something more than a fortnight got well. 
He lost his nails from the thumb and fingers that were 
ulcerated." 

The sudden disappearance of the symptoms in this case 
after the application of the escharotics to the sores is worthy 
of observation; it seems to show that they were kept up by 
the irritation of the ulcers. 

The general symptoms which I have already described 
of the cow-pox, when communicated in a casual way to any 
great extent, will, I am convinced, from the many cases I 
have seen, be found accurate; but from the very slight in- 
disposition which ensues in cases of inoculation, where the 
pustule, after affecting the constitution, quickly runs into 
a scab spontaneously, or is artificially suppressed by some 
proper application, I am induced to believe that the violence 
of the symptoms may be ascribed to the inflammation and 
irritation of the ulcers (when ulceration takes place to 
any extent, as in the casual cow-pox), and that the consti- 
tutional symptoms which appear during the presence of the 
sore, while it assumes the character of a pustule only, are 
felt but in a very trifling degree. This mild affection of the 
system happens when the disease makes but a slight local 
impression on those who have been accidentally infected 
by cows; and, as far as I have seen, it has uniformly hap- 
pened among those who have been inoculated, when a 
pustule only and no great degree of inflammation or any 
ulceration has taken place from the inoculation. The fol- 
lowing cases will strengthen this opinion. 

The cow-pox appeared at a farm in the village of Stone- 



VACCINATION AGAINST SMALLPOX 195 

house, in this county, about Michaelmas last, and con- 
tinued gradually to pass from one cow to another till the 
end of November. On the twenty-sixth of that month 
some ichorous matter was taken from a cow and dried upon 
a quill. On the 2d of December some of it was inserted 
into a scratch, made so superficial that no blood appeared, 
on the arms of Susan Phipps, a child seven years old. The 
common inflammatory appearances took place in conse- 
quence, and advanced till the fifth day, when they had so 
much subsided that I did not conceive any thing further 
would ensue. 

6th: Appearances stationary. 

7th: The inflammation began to advance. 

8th: A vesication, perceptible on the edges, forming, as 
in the inoculated smallpox, an appearance not unlike a grain 
of wheat, with the cleft, or indentation in the centre. 

9th: Pain in the axilla. 

10th: A little headache; pulse, no; tongue not discol- 
oured; countenance in health. 

nth, 12th: No perceptible illness; pulse about 100. 

13th: The pustule was now surrounded by an efflores- 
cence, interspersed with very minute confluent pustules to 
the extent of about an inch. Some of these pustules ad- 
vanced in size and maturated. So exact was the resem- 
blance of the arm at this stage to the general appearance 
of the inoculated smallpox that Mr. D., a neighbouring 
surgeon, who took some matter from it, and who had never 
seen the cow-pox before, declared he could not perceive any 
difference. 7 The child's arm now shewed a disposition to 
scab, and remained nearly stationary for two or three days, 
when it began to run into an ulcerous state, and then com- 
menced a febrile indisposition accompanied with an in- 
crease of axillary tumour. The ulcer continued spreading 
near a week, during which time the child continued ill, when 

T That the cow-pox was a supposed guardian of the constitution from the 
action of the smallpox has been a prevalent idea for a long time past; but 
the similarity in the constitutional effects between one disease and the other 
could never have been so accurately observed had not the inoculation of the 
cow-pox placed it in a new and stronger point of view. This practice, too, 
has shewn us, what before lay concealed, the rise and progress of the 
pustule formed by the insertion of the virus, which places in a most con- 
spicuous light its striking resemblance to the pustule formed from the 
inoculated smallpox. 



196 EDWARD JENNER 

it increased to a size nearly as large as a shilling. It be- 
gan now to discharge pus; granulations sprang up, and it 
healed. This child had before been of a remarkably sickly 
constitution, but is now in very high health. 

Mary Hearn, twelve years of age, was inoculated with 
matter taken from the arm of Susan Phipps. 

6th day: A pustule beginning to appear, slight pain in the 
axilla. 

7th: A distinct vesicle formed. 

8th: The vesicle increasing; edges very red; no deviation 
in its appearance at this time from the inoculated smallpox. 

9th: No indisposition; pustule advancing. 

10th : The patient felt this evening a slight febrile attack. 

nth: Free from indisposition. 

12th, 13th: The same. 

14th: An efflorescence of a faint red colour extending 
several inches round the arm. The pustule, beginning to 
shew a disposition to spread, was dressed with an ointment 
composed of hydrarg. nit. rub. and ung. ceres. The efflores- 
cence itself was covered with a plaster of ung. hydr. fort. In 
six hours it was examined, when it was found that the 
efflorescence had totally disappeared. 

The application of the ointment with the hydr. nit. rub. 
was made use of for three days, when, the state of the 
pustule remaining stationary, it was exchanged for the ung. 
hydr. nit. This appeared to have a more active effect than 
the former, and in two or three days the virus seemed to be 
subdued, when a simple dressing was made use of; but the 
sore again shewing a disposition to inflame, the ung. hydr. 
nit. was again applied, and soon answered the intended 
purpose effectually. The girl, after the tenth day, when, as 
has been observed, she became a little ill, shewed not the 
least symptom of indisposition. She was afterwards ex- 
posed to the action of variolous matter, and completely re- 
sisted it. Susan Phipps also went through a similar trial. 
Conceiving these cases to be important, I have given them 
in detail: first, to urge the precaution of using such means 
as may stop the progress of the pustule; and, secondly, to 
point out (what appears to be the fact) that the most 
material indisposition, or at least that which is felt most 



VACCINATION AGAINST SMALLPOX 197 

sensibly, does not arise primarily from the first action of 
the virus on the constitution, but that it often comes on, if 
the pustule is left to chance, as a secondary disease. This 
leads me to conjecture, what experiment must finally deter- 
mine, that they who have had the smallpox are not after- 
wards susceptible of the primary action of the cow-pox 
virus; for seeing that the simple virus itself, when it has 
not passed beyond the boundary of a vesicle, excites in the 
system so little commotion, is it not probable the trifling 
illness thus induced may be lost in that which so quickly, 
and oftentimes so severely, follows in the casual cow-pox 
from the presence of corroding ulcers? This considera- 
tion induces me to suppose that I may have been mistaken 
in my former observation on this subject. 

In this respect, as well as many others, a parallel may be 
drawn between this disease and the smallpox. In the latter, 
the patient first feels the effect of what is called the ab- 
sorption of the virus. The symptoms then often nearly re- 
tire, when a fresh attack commences, different from the 
first, and the illness keeps pace with the progress of the 
pustules through their different stages of maturation, ulcera- 
tion, etc. 

Although the application I have mentioned in the case of 
Mary Hearn proved sufficient to check the progress of 
ulceration and prevent any secondary symptoms, yet, after 
the pustule has duly exerted its influence, I should prefer 
the destroying it quickly and effectually to any other mode. 
The term caustic to a tender ear (and I conceive none feel 
more interested in this inquiry than the anxious guardians 
of a nursery) may sound harsh and unpleasing, but every 
solicitude that may arise on this account will no longer 
exist when it is understood that the pustule, in a state fit 
to be acted upon, is then quite superficial, and that it does 
not occupy the space of a silver penny. 8 

As a proof of the efficacy of this practice, even before 
the virus has fully exerted itself on the system, I shall lay 
before my reader the following history : 

8 1 mention escharotics for stopping the progress of the pustule because 
I am acquainted with their efficacy; probably more simple means might 
answer the purpose quite as well, such as might be found among the mineral 
and vegetable astringents. 



193 EDWARD JENNER 

By a reference to the treatise on the Variolar Vaccinae 
it will be seen that, in the month of April, 1798, four chil- 
dren were inoculated with the matter of cow-pox, and 
that in two of these cases the virus on the arm was de- 
stroyed soon after it had produced a perceptible sickening. 
Mary James, aged seven years, one of the children alluded 
to, was inoculated in the month of December following with 
fresh variolous matter, and at the same time was exposed 
to the effluvia of a patient affected with the smallpox. The 
appearance and progress of the infected arm was, in every 
respect, similar to that which we generally observe when 
variolous matter has been inserted into the skin of a person 
who has not previously undergone either the cow-pox or the 
smallpox. On the eighth day, conceiving there was infec- 
tion in it, she was removed from her residence among 
those who had not had the smallpox. I was now anxiously 
waiting the result, conceiving, from the state of the girl's 
arm, she would fall sick about this time. On visiting her 
on the evening of the following day (the ninth) all I could 
learn from the woman who attended her was that she felt 
somewhat hotter than usual during the night, but was not 
restless; and that in the morning there was the faint ap- 
pearance of a rash about her wrists. This went off in a 
few hours, and was not at all perceptible to me on my 
visit in the evening. Not a single eruption appeared, the 
skin having been repeatedly and carefully examined. The 
inoculated arm continued to make the usual progress to the 
end, through all the stages of inflammation, maturation, and 
scabbing. 

On the eighth day matter was taken from the arm of this 
girl (Mary James) and inserted into the arms of her mother 
and brother (neither of whom had had either the smallpox 
or the cow-pox), the former about fifty years of age, the 
latter six. 

On the eighth day after the insertion the boy felt indis- 
posed, and continued unwell two days, when a measles-like 
rash appeared on his hands and wrists, and was thinly 
scattered over his arms. The day following his body was 
marbled over with an appearance somewhat similar, but he 
did not complain, nor did he appear indisposed. A few 



YACCINATION AGAINST SMALLPOX 199 

pustules now appeared, the greater part of which went 
away without maturating. 

On the ninth day the mother began to complain. She 
was a little chilly and had a headache for two days, but no 
pustule appeared on the skin, nor had she any appearance 
of a rash. 

The family was attended by an elderly woman as a nurse, 
who in her infancy had been exposed to the contagion oi 
the smallpox, but had resisted it. This woman was now 
infected, but had the disease in the slightest manner, a very 
few eruptions appearing, two or three of which only ma- 
turated. 

From a solitary instance like that adduced of Mary James, 
whose constitution appears to have resisted the action of 
the variolous virus, after the influence of the cow-pox virus 
had been so soon arrested in its progress, no positive con- 
clusion can be fairly drawn; nor from the history of the 
three other patients who were subsequently infected, but, 
nevertheless, the facts collectively may be deemed inter- 
esting. 

That one mild variety of the smallpox has appeared I 
have already plainly shewn; 9 and by the means now men- 
tioned we probably have it in our power to produce at will 
another. 

At the time when the pustule was destroyed in the arm of 
Mary James I was informed she had been indisposed about 
twelve hours; but I am now assured by those who were 
with her that the space of time was much less. Be that as 
it may, in cases of cow-pox inoculation I would not recom- 
mend any application to subdue the action of the pustule 
until convincing proofs had appeared of the patient's hav- 
ing felt its effects at least twelve hours. No harm, indeed, 
could ensue were a longer period to elapse before the appli- 
cation was made use of. In short, it should be suffered to 
have as full an effect as it could, consistently with the state 
of the arm. 

As the cases of inoculation multiply, I am more and more 
convinced of the extreme mildness of the symptoms arising 

8 See Inquiry into the Causes and Effects of the Variolae Vaccina^ p. 54 
(of original article). 



200 EDWARD JENNER 

merely from the primary action of the virus on the con- 
stitution, and that those symptoms which, as in the acci- 
dental cow-pox, affect the patient with severity, are entirely 
secondary, excited by the irritating processes of inflamma- 
tion and ulceration; and it appears to me that this singular 
virus possesses an irritating quality of a peculiar kind, but 
as a single cow-pox pustule is all that is necessary to render 
the variolous virus ineffectual, and as we possess the means 
of allaying the irritation, should any arise, it becomes of 
little or no consequence. 

It appears then, as far as an inference can be drawn from 
the present progress of cow-pox inoculation, that it is an 
accidental circumstance only which can render this a vio- 
lent disease, and a circumstance of that nature which, for- 
tunately, it is in the power of almost every one to avoid. I 
allude to the communication of the disease from cows. In 
this case, should the hands of the milker be affected with 
little accidental sores to any extent, every sore would be- 
come the nidus of infection and feel the influence of the 
virus; and the degree of violence in the constitutional symp- 
toms would be in proportion to the number and to the state 
of these local affections. Hence it follows that a person, 
either by accident or design, might be so filled with these 
wounds from contact with the virus that the constitution 
might sink under the pressure. 

Seeing that we possess the means of rendering the action 
of the sores mild, which, when left to chance, are capable 
of producing violent effects; and seeing, too, that these 
sores bear a resemblance to the smallpox, especially the 
confluent, should it not encourage the hope that some topi- 
cal application might be used with advantage to counteract 
the fatal tendency of that disease, when it appears in this 
terrific form? At what stage or stages of the disease this 
may be done with the most promising expectation of suc- 
cess I will not pretend now to determine. I only throw out 
this idea as the basis of further reasoning and experiment. 

I have often been foiled in my endeavours to communi- 
cate the cow-pox by inoculation. An inflammation will 
sometimes succeed the scratch or puncture, and in a few 
days disappear without producing any further effect. Some- 



VACCINATION AGAINST SMALLPOX 201 

times it will even produce an ichorous fluid, and yet the 
system will not be affected. The same thing we know hap- 
pens with the smallpox virus. 

Four or five servants were inoculated at a farm contiguous 
to this place, last summer, with matter just taken from an 
infected cow. A little inflammation appeared on all their 
arms, but died away without producing a pustule; yet all 
these servants caught the disease within a month after- 
wards from milking the infected cows, and some of them 
had it severely. At present no other mode than that com- 
monly practiced for inoculating the smallpox has been used 
for giving the cow-pox; but it is probable this might be 
varied with advantage. We should imitate the casual com- 
munication more clearly were we first, by making the 
smallest superficial incision or puncture on the skin, to pro- 
duce a little scab, and then, removing it, to touch the abraded 
part with the virus. A small portion of a thread imbrued 
in the virus (as in the old method of inoculating the small- 
pox) and laid upon the slightly incised skin might probably 
prove a successful way of giving the disease; or the cutis 
might be exposed in a minute point by an atom of blistering 
plaster, and the virus brought in contact with it. In the 
cases just alluded to, where I did not succeed in giving the 
disease constitutionally, the experiment was made with 
matter taken in a purulent state from a pustule on the 
nipple of a cow. 

Is pure pas, though contained in a smallpox pustule, ever 
capable of producing the smallpox perfectly? I suspect it 
is not. Let us consider that it is always preceded by the 
limpid fluid, which, in constitutions susceptible of variolous 
contagion, is always infectious; and though, on opening 
a pustule, its contents may appear perfectly purulent, yet a 
given quantity of the limpid fluid may, at the same time, 
be blended with it, though it would be imperceptible to the 
only test of our senses, the eye. The presence, then, of this 
fluid, or its mechanical diffusion through pus, may at all 
times render active what is apparently mere pus, while its 
total absence (as in stale pustules) may be attended with 
the imperfect effects we have seen. 

It would be digressing too widely to go far into the 



202 EDWARD JENNER 

doctrine of secretion, but as it will not be quite extraneous, 
I shall just observe that I consider both the pus and the 
limpid fluid of the pustule as secretions, but that the organs 
established by nature to perform the office of secreting these 
fluids may differ essentially in their mechanical structure. 
What but a difference in the organization of glandular bodies 
constitutes the difference in the qualities of the fluids 
secreted? From some peculiar derangement in the struc- 
ture or, in other words, some deviation in the natural action 
of a gland destined to create a mild, innoxious fluid, a 
poison of the most deadly nature may be created; for ex- 
ample: That gland, which in its sound state secretes pure 
saliva, may, from being thrown into diseased action, pro- 
duce a poison of the most destructive quality. Nature ap- 
pears to have no more difficulty in forming minute 
glands among the vascular parts of the body than she has 
in forming blood vessels, and millions of these can be 
called into existence, when inflammation is excited, in a 
few hours. 10 

In the present early stage of the inquiry (for early it 
certainly must be deemed), before we know for an abso- 
lute certainty how soon the virus of the cow-pox may suf- 
fer a change in its specific properties, after it has quitted the 
limpid state it possesses when forming a pustule, it would 
be prudent for those who have been inoculated with it to 
submit to variolous inoculation. No injury or inconvenience 
can accrue from this; and were the same method practiced 
among those who, from inoculation, have felt the smallpox 
in an unsatisfactory manner at any period of their lives, it 
might appear that I had not been too officious in offering 
a cautionary hint in recommending a second inoculation with 
matter in its most perfect state. 

And here let me suppose, for argument's sake (not from 
conviction), that one person in an hundred after having had 
the cow-pox should be found susceptible of the smallpox, 
would this invalidate the utility of the practice? For, waiv- 
ing all other considerations, who will deny that the inoculated 
smallpox, although abstractedly it may be considered as 

10 Mr. Home, In his excellent dissertation on pus and mucus, justifies this 
assertion. 



VACCINATION AGAINST SMALLPOX 203 

harmless, does not involve in itself something that in number- 
less instances proves baneful to the human frame. 

That in delicate constitutions it sometimes excites scrofula 
is a fact that must generally be subscribed to, as it is so 
obvious to common observation. This consideration is im- 
portant. 

As the effects of the smallpox inoculation on those who 
have had the cow-pox will be watched with the most scrupu- 
lous eye by those who prosecute this inquiry, it may be 
proper to bring to their recollection some facts relative to 
the smallpox, which I must consider here as of consequence, 
but which hitherto seem not to have made a due impression. 

It should be remembered that the constitution cannot, by 
previous infection, be rendered totally unsusceptible of the 
variolous poison ; neither the casual nor the inoculated small- 
pox, whether it produces the disease in a mild or in a violent 
way, can perfectly extinguish the susceptibility. The skin, 
we know, is ever ready to exhibit, though often in a very 
limited degree, the effects of the poison when inserted there ; 
and how frequently do we see, among nurses, when much 
exposed to the contagion, eruptions, and these sometimes 
preceded by sensible illness! yet should any thing like an 
eruption appear, or the smallest degree of indisposition, upon 
the insertion of the variolous matter on those who have gone 
through the cow-pox, my assertions respecting the peculiar- 
ities of the disease might be unjustly discredited. 

I know a gentleman who, many years ago, was inoculated 
for the smallpox, but having no pustules, or scarcely any con- 
stitutional affection that was perceptible, he was dissatisfied, 
and has since been repeatedly inoculated. A vesicle has 
always been produced in the arm in consequence, with axil- 
lary swelling and a slight indisposition ; this is by no means 
a rare occurrence. It is probable that fluid thus excited upon 
the skin would always produce the smallpox. 

On the arm of a person who had gone through the cow- 
pox many years before I once produced a vesication by the 
insertion of variolous matter, and, with a little of the fluid, 
inoculated a young woman who had a mild, but very effica- 
cious, smallpox in consequence, although no constitutional 
effect was produced on the patient from whom the matter 



204 EDWARD JENNER 

was taken. The following communication from Mr. Fewster 
affords a still clearer elucidation of this fact. Mr. Fewster 

says: "On the 3d of April, 1797, I inoculated Master H , 

aged fourteen months, for the smallpox. At the usual time 
he sickened, had a plentiful eruption, particularly on his face, 
and got well. His nursemaid, aged twenty-four, had many 
years before gone through the smallpox, in the natural way, 
which was evident from her being much pitted with it She 
had used the child to sleep on her left arm, with her left 
cheek in contact with his face, and during his inoculation he 
had mostly slept in that manner. About a week after the 
child got well she (the nurse) desired me to look at her face, 
which she said was very painful There was a plentiful 
eruption on the left cheek, but not on any other part of the 
body, which went on to maturation. 

"On enquiry I found that three days before the appearance 
of the eruption she was taken with slight chilly fits, pain in 
her head and limbs, and some fever. On the appearance of 
the eruption these pains went off, and now, the second day 
of the eruption, she complains of a little sore throat. 
Whether the above symptoms are the effects of the smallpox 
or a recent cold I do not know. On the fifth day of the 
eruption I charged a lancet from two of the pustules, and 
on the next day I inoculated two children, one two years, the 
other four months old, with the matter. At the same time 
I inoculated the mother and eldest sister with variolous 

matter taken from Master H . On the fifth day of their 

inoculation all their arms were inflamed alike; and on the 
eighth day the eldest of those inoculated from the nurse 
sickened, and the youngest on the eleventh. They had both a 
plentiful eruption, from which I inoculated several others, 
who had the disease very favourably. The mother and the 
other child sickened about the same time, and likewise had 
a plentiful eruption. 

"Soon after, a man in the village sickened with the small- 
pox and had a confluent kind. To be convinced that the 
children had had the disease effectually I took them to his 
house and inoculated them in both arms with matter laken 
from him, but without effect." 

These are not brought forward as uncommon occurrences, 



VACCINATION AGAINST SMALLPOX 205 

but as exemplifications of the human system's susceptibility 
of the variolous contagion, although it has been previously 
sensible of its action. 

Happy is it for mankind that the appearance of the small- 
pox a second time on the same person, beyond a trivial 
extent, is so extremely rare that it is looked upon as a 
phenomenon! Indeed, since the publication of Dr. Heber- 
den's paper on the Varicella, or chicken-pox, the idea of 
such an occurrence, in deference to authority so truly 
respectable, has been generally relinquished. This I conceive 
has been without just reason; for after we have seen, among 
many others, so strong a case as that recorded by Mr. 
Edward Withers, Surgeon, of Newbury, Berks, in the fourth 
volume of the Memoirs of the Medical Society of London 
(from which I take "the following extracts), no one, I think, 
will again doubt the fact. 

" Mr. Richard Langford, a farmer of West Shefford, in 
this county (Berks), about fifty years of age, when about 
a month old had the smallpox at a time when three others 
of the family had the same disease, one of whom, a servant 
man, died of it. Mr. Langford's countenance was strongly 
indicative of the malignity of the distemper, his face being 
so remarkably pitted and seamed as to attract the notice of 
all who saw him, so that no one could entertain a doubt of 
his having had that disease in a most inveterate manner." 
Mr. Withers proceeds to state that Mr. Langford was seized 
a second time, had a bad confluent smallpox, and died on the 
twenty-first day from the seizure; and that four of the 
family, as also a sister of the patient's, to whom the disease 
was conveyed by her son's visiting his uncle, falling 
down with the smallpox, fully satisfied the country with 
regard to the nature of the disease, which nothing short of 
this would have done; the sister died. 

" This case was thought so extraordinary a one as to in- 
duce the rector of the parish to record the particulars in the 
parish register." 

It is singular that in most cases of this kind the disease in 
the first instance has been confluent; so that the extent of 
the ulceration on the skin (as in the cow-pox) is not the 
process in nature which affords security to the constitution. 



206 EDWARD JENNER 

As the subject of the smallpox is so interwoven with that 
which is the more immediate object of my present concern, 
it must plead my excuse for so often introducing it. At 
present it must be considered as a distemper not well under- 
stood. The inquiry I have instituted into the nature of the cow- 
pox will probably promote its more perfect investigation. 

The inquiry of Dr. Pearson into the history of the cow-pox 
having produced so great a number of attestations in favour 
of my assertion that it proves a protection to the human 
body from the smallpox, I have not been assiduous in seek- 
ing for more; but as some of my friends have been so good 
as to communicate the following, I shall conclude these 
observations with their insertion. 

Extract of a letter from Mr. Drake, Surgeon, at Stroud, 
in this county, and late Surgeon to the North Gloucester 
Regiment of Militia: 

"In the spring of the year 1796 I inoculated men, women, 
and children to the amount of about seventy. Many of the 
men did not receive the infection, although inoculated at least 
three times and kept in the same room with those who 
actually underwent the disease during the whole time occu- 
pied by them in passing through it. Being anxious they 
should, in future, be secure against it, I was very particular 
in my inquiries to find out whether they ever had previously 
had it, or at any time been in the neighbourhood of people 
labouring under it. But, after all, the only satisfactory in- 
formation I could obtain was that they had had the cow-pox. 
As I was then ignorant of such a disease affecting the human 
subject, I flattered myself what they imagined to be the cow- 
pox was in reality the smallpox in a very slight degree. I 
mentioned the circumstance in the presence of the officers, 
at the time expressing my doubts if it were not smallpox, 
and was not a little surprised when I was told by the Colonel 
that he had frequently heard you mention the cow-pox as 
a disease endemial to Gloucestershire, and that if a person 
were ever affected by it, you supposed him afterwards secure 
from the smallpox. This excited my curiosity, and when I 
visited Gloucestershire I was very inquisitive concerning the 
subject, and from the information I have since received, 
both from your publication and from conversation with med- 



VACCINATION AGAINST SMALLPOX 207 

ical men of the greatest accuracy in their observations, I am 
fully convinced that what the men supposed to be cow-pox 
was actually so, and I can safely affirm that they effectually 
resisted the smallpox." 

Mr. Fry, Surgeon, at Dursley in this county, favours me 
with the following communication: 

" During the spring of the year 1797 I inoculated fourteen 
hundred and seventy-five patients, of all ages, from a fort- 
night old to seventy years ; amongst whom there were many 
who had previously gone through the cow-pox. The exact 
number I cannot state ; but if I say there were nearly thirty, 
I am certainly within the number. There was not a single 
instance of the variolous matter producing any constitutional 
effect on these people, nor any greater degree of local in- 
flammation than it would have done in the arm of a person 
who had before gone through the smallpox, notwithstanding 
it was invariably inserted four, five, and sometimes six 
different times, to satisfy the minds of the patients. In the 
common course of inoculation previous to the general one 
scarcely a year passed without my meeting with one or two 
instances of persons who had gone through the cow-pox, 
resisting the action of the variolous contagion. I may fairly 
say that the number of people I have seen inoculated with 
the smallpox who, at former periods, had gone through the 
cow-pox, are not less than forty ; and in no one instance have 
I known a patient receive the smallpox, notwithstanding they 
invariably continued to associate with other inoculated 
patients during the progress of the disease, and many of 
them purposely exposed themselves to the contagion of the 
natural smallpox ; whence I am fully convinced that a person 
who had fairly had the cow-pox is no longer capable of being 
acted upon by the variolous matter. 

"I also inoculated a very considerable number of those 
who had had a disease which ran through the neighbourhood 
a few years ago, and was called by the common people the 
swine-pox, not one of whom received the smallpox." 

"There were about half a dozen instances of people who 
never had either the cow- or swine-pox, yet did not receive 

u This was that mild variety of the smallpox which I have noticed in the 
late Treatise on the Cow-Pox (p. 233). 



208 EDWARD JENNER 

the smallpox, the system not being in the least deranged, or 
the arms inflamed, although they were repeatedly inoculated, 
and associated with others who were labouring under the 
disease ; one of them was the son of a farrier." 

Mr. Tierny, Assistant Surgeon of the South Gloucester 
Regiment of Militia, has obliged me with the following in- 
formation: 

" That in the summer of the year of 1798 he inoculated a 
great number of the men belonging to the regiment, and that 
among them he found eleven who, from having lived in 
dairies, had gone through the cow-pox. That all of them 
resisted the smallpox except one, but that on making the most 
rigid and scrupulous enquiry at the farm in Gloucestershire, 
where the man said he lived when he had the disease, and 
among those with whom, at the same time, he declared he 
had associated, and particularly of a person in the parish, 
whom he said had dressed his fingers, it most clearly appeared 
that he aimed at an imposition, and that he never had been 
affected with the cow-pox." 12 Mr. Tierny remarks that the 
arms of many who were inoculated after having had the 
cow-pox inflamed very quickly, and that in several a little 
ichorous fluid was formed. 

Mr. Cline, who in July last was so obliging at my request 
as to try the efficacy of the cow-pox virus, was kind enough 
to give me a letter on the result of it, from which the follow- 
ing is an extract: 

"My Dear Sir: 

" The cow-pox experiment has succeeded admirably. The 
child sickened on the seventh day, and the fever, which was 
moderate, subsided on the eleventh. The inflammation aris- 
ing from the insertion of the virus extended to about four 
inches in diameter, and then gradually subsided, without hav- 
ing been attended with pain or other inconvenience. There 
were no eruptions. 

"I have since inoculated him with smallpox matter in three 
places, which were slightly inflamed on the third day, and 
then subsided. 

13 The public cannot be too much upon their guard respecting persons of 
this description. 



VACCINATION AGAINST SMALLPOX 209 

"Dr. Lister, who was formerly physician to the Smallpox 
Hospital, attended the child with me, and he is convinced that 
it is not possible to give him the smallpox. I think the sub- 
stituting the cow-pox poison for the smallpox promises to be 
one of the greatest improvements that has ever been made 
in medicine; and the more I think on the subject, the more 
I am impressed with its importance. 

"With great esteem 
"I am, etc., 

"Henry Cline. 
"Lincoln's Inn Fields, 
August 2, 1798." 

From communications, with which I have been favoured 
from Dr. Pearson, who has occasionally reported to me the 
result of his private practice with the vaccine virus in 
London, and from Dr. Woodville, who also has favoured 
me with an account of his more extensive inoculation 
with the same virus at the Smallpox Hospital, it appears 
that many of their patients have been affected with erup- 
tions, and that these eruptions have maturated in a man- 
ner very similar to the variolous. The matter they made 
use of was taken in the first instance from a cow be- 
longing to one of the great milk farms in London. Having 
never seen maturated pustules produced either in my own 
practice among those who were casually infected by cows, 
or those to whom the disease had been communicated by 
inoculation, I was desirous of seeing the effect of the mat- 
ter generated in London, on subjects living in the country. 
A thread imbrued in some of this matter was sent to me, 
and with it two children were inoculated, whose cases I 
shall transcribe from my notes. 

Stephen Jenner, three years and a half old. 

3d day: The arm shewed a proper and decisive inflam- 
mation. 

6th: A vesicle arising. 

7th : The pustule of a cherry colour. 

8th: Increasing in elevation. A few spots now appear 
on each arm near the insertion of the inferior tendons 
of the biceps muscles. They are very small and of a 



210 EDWARD JENNER 

vivid red colour. The pulse natural; tongue of its natural 
hue; no loss of appetite or any symptom of indisposition. 

9th: The inoculated pustule on the arm this evening 
began to inflame, and gave the child uneasiness; he cried 
and pointed to the seat of it, and was immediately after- 
wards affected with febrile symptoms. At the expiration 
of two hours after the seizure a plaster of ung. hydrarg. 
fort, was applied, and its effect was very quickly per- 
ceptible, for in ten minutes he resumed his usual looks 
and playfulness. On examining the arm about three hours 
after the application of the plaster its effects in subduing 
the inflammation were very manifest. 

10th: The spots on the arms have disappeared, but there 
are three visible in the face. 

nth: Two spots on the face are gone; the other barely 
perce tible. 

13th: The pustule delineated in the second plate in the 
Treatise on the Variolae Vaccinas is a correct representa- 
tion of that on the child's arm as it appears at this time. 

14th: Two fresh spots appear on the face. The pustule 
on the arm nearly converted into a scab. As long as any 
fluid remained in it it was limpid. 

James Hill, four years old, was inoculated on the same 
day, and with part of the same matter which infected 
Stephen Jenner. It did not appear to have taken effect 
till the fifth day. 

7th : A perceptible vesicle : this evening the patient became 
a little chilly ; no pain or tumour discoverable in the axilla. 

8th: Perfectly well. 

9th: The same. 

10th: The vesicle more elevated than I have been ac- 
customed to see it, and assuming more perfectly the vario- 
lous character than is common with the cow-pox at this 
stage. 

nth: Surrounded by an inflammatory redness, about the 
size of a shilling, studded over with minute vesicles. The 
pustule contained a limpid fluid till the fourteenth day, after 
which it was incrusted over in the usual manner ; but this in- 
crustation or scab being accidentally rubbed off, it was 
slow in healing. 



VACCINATION AGAINST SMALLPOX 211 

These children were afterwards fully exposed to the 
smallpox contagion without effect. 

Having been requested by my friend, Mr. Henry Hicks, 
of Eastington, in this county, to inoculate two of his chil- 
dren, and at the same time some of his servants and the 
people employed in his manufactory, matter was taken 
from the arm of this boy for the purpose. The num- 
bers inoculated were eighteen. They all took the infec- 
tion, and either on the fifth or sixth day a vesicle was 
perceptible on the punctured part. Some of them began 
to feel a little unwell on the eighth day, but the greater 
number on the ninth. Their illness, as in the former cases 
described, was of short duration, and not sufficient to in- 
terrupt, but at very short intervals, the children from their 
amusements, or the servants and manufacturers from fol- 
lowing their ordinary business. 

Three of the children whose employment in the manu- 
factory was in some degree laborious had an inflammation 
on their arms beyond the common boundary about the 
eleventh or twelfth day, when the feverish symptoms, which 
before were nearly gone off, again returned, accompanied 
with increase of axillary tumour. In these cases (clearly 
perceiving that the symptoms were governed by the state 
of the arms) I applied on the inoculated pustules, and 
renewed the application three or four times within an 
hour, a pledget of lint, previously soaked in aqua lythargyri 
acetati™ and covered the hot efflorescence surrounding them 
with cloths dipped in cold water. 

The next day I found this simple mode of treatment 
had succeeded perfectly. The inflammation was nearly 
gone off, and with it the symptoms which it had pro- 
duced. 

Some of these patients have since been inoculated with 
variolous matter, without any effect beyond a little in- 
flammation on the part where it was inserted. 

Why the arms of those inoculated with the vaccine mat- 
ter in the country should be more disposed to inflame than 
those inoculated in London it may be difficult to determine. 
From comparing my own cases with some transmitted to 
^Goulard's extract of Saturn. 



212 EDWARD JENNER 

me by Dr. Pearson and Dr. Woodville, this appears to 
be the fact; and what strikes me as still more extraordin- 
ary with respect to those inoculated in London is the ap- 
pearance of maturating eruptions, In the two instances 
only which I have mentioned (the one from the inoculated, 
the other from the casual, cow-pox) a few red spots ap- 
peared, which quickly went off without maturating. The 
case of the Rev. Mr. Moore's servant may, indeed, seem 
like a deviation from the common appearances in the coun- 
try, but the nature of these eruptions was not ascertained 
beyond their not possessing the property of communicat- 
ing the disease by their effluvia. Perhaps the difference 
we perceive may be owing to some variety in the mode 
of action of the virus upon the skin of those who breathe 
the air of London and those who live in the country. That 
the erysipelas assumes a different form in London from 
what we see it put on in this country is a fact very gen- 
erally acknowledged. In calling the inflammation that is 
excited by the cow-pox virus erysipelatous, perhaps I may 
not be critically exact, but it certainly approaches near 
to it Now, as the diseased action going forward in the 
part infected with the virus may undergo different modi- 
fications according to the peculiarities of the constitution 
on which it is to produce its effect, may it not account 
for the variation which has been observed? 

To this it may probably be objected that some of the 
patients inoculated, and who had pustules in consequence, 
were newly come from the country; but I conceive that 
the changes wrought in the human body through the medium 
of the lungs may be extremely rapid. Yet, after all, further 
experiments made in London with vaccine virus generated 
in the country must finally throw a light on what now 
certainly appears obscure and mysterious. 

The principal variation perceptible to me in the action 
of the vaccine virus generated in London from that pro- 
duced in the country was its proving more certainly in- 
fectious and giving a less disposition in the arm to inflame. 
There appears also a greater elevation of the pustule above 
the surrounding skin. In my former cases the pustule 
produced by the insertion of the virus was more like one 



VACCINATION AGAINST SMALLPOX 213 

of those which are so thickly spread over the body in 
a bad kind of confluent smallpox. This was more like a 
pustule of the distinct smallpox, except that I saw no in- 
stance of pus being formed in it, the matter remaining 
limpid till the period of scabbing. 

Wishing to see the effects of the disease on an infant 
newly born, my nephew, Mr. Henry Jenner, at my request, 
inserted the vaccine virus into the arm of a child about 
twenty hours old. His report to me is that the child 
went through the disease without apparent illness, yet that 
it was found effectually to resist the action of variolous 
matter with which it was subsequently inoculated. 

I have had an opportunity of trying the effects of the 
cow-pox matter on a boy, who, the day preceding its in- 
sertion, sickened with the measles. The eruption of the 
measles, attended with cough, a little pain in the chest, 
and the usual symptoms accompanying the disease, ap- 
peared on the third day and spread all over him. The 
disease went through its course without any deviation from 
its usual habits; and, notwithstanding this, the cow-pox 
virus excited its common appearances, both on the arm 
and on the constitution, without any febrile interruption; 
on the sixth day there was a vesicle. 

8th : Pain in the axilla, chilly, and affected with headache. 

9th: Nearly well. 

12th: The pustule spread to the size of a large split-pea, 
but without any surrounding efflorescence. It soon after- 
wards scabbed, and the boy recovered his general health 
rapidly. But it should be observed that before it scabbed 
the efflorescence which had suffered a temporary suspension 
advanced in the usual manner. 

Here we see a deviation from the ordinary habits of 
the smallpox, as it has been observed that the presence of 
the measles suspends the action of the variolous matter. 

The very general investigation that is now taking place, 
chiefly through inoculation (and I again repeat my earnest 
hope that it may be conducted with that calmness and 
moderation which should ever accompany a philosophical 
research), must soon place the vaccine disease in its just 
point of view. The result of all my trials with the virus 

(14) hc xxxvm 



214 EDWARD JENNER 

on the human subject has been uniform. In every instance 
the patient who has felt its influence, has completely lost 
the susceptibility for the variolous contagion; and as these 
instances are now become numerous, I conceive that, joined 
to the observations in the former part of this paper, they 
sufficiently preclude me from the necessity of entering into 
controversies with those who have circulated reports ad- 
verse to my assertions, on no other evidence than what 
has been casually collected. 

Ill 

A Continuation of Facts and Observations Relative 
to the Variola Vaccinae, or Cow-pox. 1800 

Since my former publications on the vaccine inoculation 
I have had the satisfaction of seeing it extend very widely. 
Not only in this country is the subject pursued with ar- 
dour, but from my correspondence with many respectable 
medical gentlemen on the Continent (among whom are Dr. 
De Carro, of Vienna, and Dr. Ballhorn, of Hanover) I 
find it is as warmly adopted abroad, where it has afforded 
the greatest satisfaction. I have the pleasure, too, of see- 
ing that the feeble efforts of a few individuals to depreciate 
the new practice are sinking fast into contempt beneath 
the immense mass of evidence which has arisen up in 
support of it, 

Upwards of six thousand persons have now been inocu- 
lated with the virus of cow-pox, and the far greater part 
of them have since been inoculated with that of small- 
pox, and exposed to its infection in every rational way 
that could be devised, without effect. 

It was very improbable that the investigation of a 
disease so analogous to the smallpox should go forward 
without engaging the attention of the physician of the 
Smallpox Hospital in London. 

Accordingly, Dr. Woodville, who fills that department 
with so much respectability, took an early opportunity 
of instituting an inquiry into the nature of the cow-pox. 
This inquiry was begun in the early part of the present 
year, and in May, Dr. Woodville published the result, 



VACCINATION AGAINST SMALLPOX 215 

which differs essentially from mine in a point of much 
importance. It appears that three-fifths of the patients 
inoculated were affected with eruptions, for the most part 
so perfectly resembling the smallpox as not to be dis- 
tinguished from them. On this subject it is necessary 
that I should make some comments. 

When I consider that out of the great number of cases 
of casual inoculation immediately from cows which from 
time to time presented themselves to my observation, and 
the many similar instances which have been communicated 
to me by medical gentlemen in this neighbourhood; when 
I consider, too, that the matter with which my inocula- 
tions were conducted in the years 1797, '98, and '99, was 
taken from some different cows, and that in no instance 
any thing like a variolous pustule appeared, I cannot feel 
disposed to imagine that eruptions, similar to those de- 
scribed by Dr. Woodville, have ever been produced by the 
pure uncontaminated cow-pock virus; on the contrary, I 
do suppose that those which the doctor speaks of originated 
in the action of variolous matter which crept into the 
constitution with the vaccine. And this I presume hap- 
pened from the inoculation of a great number of the pa- 
tients with variolous matter (some on the third, others on 
the fifth, day) after the vaccine had been applied; and 
it should be observed that the matter thus propagated be- 
came the source of future inoculations in the hands of 
many medical gentlemen who appeared to have been pre- 
viously unacquainted with the nature of the cow-pox. 

Another circumstance strongly, in my opinion, support- 
ing this supposition is the following: The cow-pox has 
been known among our dairies time immemorial. If pus- 
tules, then, like the variolous, were to follow the com- 
munication of it from the cow to the milker, would not 
such a fact have been known and recorded at our farms? 
Yet neither our farmers nor the medical people of the neigh- 
bourhood have noticed such an occurrence. 

A few scattered pimples I have sometimes, though very 
rarely, seen, the greater part of which have generally 
disappeared quickly, but some have remained long enough 
to suppurate at their apex, That local cuticular inflam- 



216 EDWARD JENNER 

mation, whether springing up spontaneously or arising 
from the application of acrid substances, such for instance, 
as cantharides, pix Burgundica, antimonium tartarizatum, 
etc., will often produce cutaneous affections, not only near 
the seat of the inflammation, but on some parts of the 
skin far beyond its boundary, is a well-known fact. It is, 
doubtless, on this principle that the inoculated cow-pock 
pustule and its concomitant efflorescence may, in very ir- 
ritable constitutions, produce this affection. The eruption 
I allude to has commonly appeared some time in the third 
week after inoculation. But this appearance is too trivial 
to excite the least regard. 

The change which took place in the general appear- 
ance during the progress of the vaccine inoculation at the 
Smallpox Hospital should likewise be considered. 

Although at first it took on so much of the variolous 
character as to produce pustules in three cases out of 
five, yet in Dr. Woodville's last report, published in June, 
he says : " Since the publication of my reports of inocu- 
lations for the cow-pox, upwards of three hundred cases 
have been under my care; and out of this number only 
thirty-nine had pustules that suppurated; viz., out of the 
first hundred, nineteen had pustules; out of the second, 
thirteen; and out of the last hundred and ten, only seven 
had pustules. Thus it appears that the disease has be- 
come considerably milder; which I am inclined to attribute 
to a greater caution used in the choice of the matter, with 
which the infection was communicated; for, lately, that 
which has been employed for this purpose has been taken 
only from those patients in whom the cow-pox proved 
very mild and well characterized." 1 

The inference I am induced to draw from these premises 
is very different The decline, and, finally, the total ex- 
tinction nearly, of these pustules, in my opinion, are more 
fairly attributable to the cow-pox virus, assimilating the 
variolous, 2 the former probably being the original, the lat- 

1 In a few weeks after the cow-pox inoculation was introduced at the 
Smallpox Hospital I was favoured with some virus from this stock. In the 
first instance it produced a few pustules, which did not maturate; but in 
the subsequent cases none appeared. — E. J. 

3 In my first publication on this subject I expressed an opinion that the 
smallpox and the cow-pox were the same diseases under different modifica- 



VACCINATION AGAINST SMALLPOX 217 

ter the same disease under a peculiar, and at present an 
inexplicable, modification. 

One experiment tending to elucidate the point under 
discussion I had myself an opportunity of instituting. On 
the supposition of its being possible that the cow which 
ranges over the fertile meadows in the vale of Gloucester 
might generate a virus differing in some respects in its 
qualities from that produced by the animal artificially pam- 
pered for the production of milk for the metropolis, I pro- 
cured, during my residence there in the spring, some cow 
pock virus from a cow at one of the London milk- farms." 
It was immediately conveyed into Gloucestershire to Dr. 
Marshall, who was then extensively engaged in the inocu- 
lation of the cow-pox, the general result of which, and 
of the inoculation in particular with this matter, I shall 
lay before my reader in the following communication from 
the doctor: 

"Dear Sir: 

" My neighbour, Mr. Hicks, having mentioned your wish 
to be informed of the progress of the inoculation here for 
the cow-pox, and he also having taken the trouble to 
transmit to you my minutes of the cases which have fallen 
under my care, I hope you will pardon the further trouble 
I now give you in stating the observations I have made upon 
the subject. When first informed of it, having two chil- 
dren who had not had the smallpox, I determined to inocu- 
late them for the cow-pox whenever I should be so fortunate 
as to procure matter proper for the purpose. I was, there- 
fore, particularly happy when I was informed that I could 
procure matter from some of those whom you had in- 
oculated. In the first instance I had no intention of extend- 
ing the disease further than my own family, but the very 
extensive influence which the conviction of its efficacy in 
resisting the smallpox has had upon the minds of the 
people in general has rendered that intention nugatory, as 

tions. In this opinion Dr. Woodville has concurred. The axiom of the im- 
mortal Hauter, that two diseased actions cannot take place at the same time 
in one and the same part, will not be injured by the admission of this theory. 
8 It was taken by Mr. Tanner, then "a student at the Veterinary College, 
from a cow at Mr. Clark's farm at Kentish Town. 



218 EDWARD JENNER 

you will perceive, by the continuation of my cases enclosed 
in this letter, 4 by which it will appear that since the 22d of 
March I have inoculated an hundred and seven persons; 
which, considering the retired situation I resided in, is a 
very great number. There are also other considerations 
which, besides that of its influence in resisting the small- 
pox, appear to have had their weight; the peculiar mild- 
ness of the disease, the known safety of it, and its not 
having in any instance prevented the patient from fol- 
lowing his ordinary business. In all the cases under my 
care there have only occurred two or three which required 
any application, owing to erysipelatous inflammation on 
the arm, and they immediately yielded to it. In the re- 
mainder the constitutional illness has been slight but suf- 
ficiently marked, and considerably less than I ever ob- 
served in the same number inoculated with the smallpox. 
In only one or two of the cases have any other eruptions 
appeared than those around the spot where the matter was 
inserted, and those near the infected part. Neither does 
there appear in the cow-pox to be the least exciting cause 
to any other disease, which in the smallpox has been 
frequently observed, the constitution remaining in as full 
health and vigour after the termination of the disease as 
before the infection. Another important consideration ap- 
pears to be the impossibility of the disease being com- 
municated except by the actual contact of the matter of the 
pustule, and consequently the perfect safety of the re- 
maining part of the family, supposing only one or two 
should wish to be inoculated at the same time. 

"Upon the whole, it appears evident to me that the 
cow-pox is a pleasanter, shorter, and infinitely more safe 
disease than the inoculated smallpox when conducted in 
the most careful and approved manner; neither is the local 
affection of the inoculated part, or the constitutional ill- 
ness, near so violent. I speak with confidence on the sub- 
ject, having had an opportunity of observing its effects 
upon a variety of constitutions, from three months old 
to sixty years; and to which I have paid particular at- 

* Doctor Marshall has detailed these cases with great accuracy, but their 
publication would hoay be deemed superfluous,— -E, J, 



VACCINATION AGAINST SMALLPOX 219 

tention. In the cases alluded to here you will observe that 
the removal from the original source of the matter had 
made no alteration or change in the nature or appearance 
of the disease, and that it may be continued, ad infinitum 
(I imagine), from one person to another (if care be ob- 
served in taking the matter at a proper period) without 
any necessity of recurring to the original matter of the 
cow. 

" I should be happy if any endeavours of mine could 
tend further to elucidate the subject, and shall be much 
gratified is sending you any further observations I may 
be enabled to make. 

" I have the pleasure to subscribe myself, 
" Dear sir, etc., 

"Joseph H. Marshall. 

" Eastington, Gloucestershire, April 26, 1799." 

The gentleman who favoured me with the above ac- 
count has continued to prosecute his inquiries with un- 
remitting industry, and has communicated the result in an- 
other letter, which at his request I lay before the public 
without abbreviation. 

Dr. Marshall's second letter: 

"Dear Sir: 

" Since the date of my former letter I have continued 
to inoculate with the cow-pox virus. Including the cases 
before enumerated, the number now amounts to four hun- 
dred and twenty-three. It would be tedious and useless 
to detail the progress of the disease in each individual- — 
it is sufficient to observe that I noticed no deviation in any 
respect from the cases I formerly adduced. The general 
appearances of the arm exactly corresponded with the ac- 
count given in your first publication. When they were 
disposed to become troublesome by erysipelatous inflam- 
mation, an application of equal parts of vinegar and water 
always answered the desired intention. I must not omit 
to inform you that when the disease had duly acted upon 
the constitution I have frequently used the vitriolic acid. 
A portion of a drop applied with the head of a probe or 



220 EDWARD JENNER 

any convenient utensil upon the pustule, suffered to re- 
main about forty seconds, and afterwards washed off with 
sponge and water, never failed to stop its progress and 
expedite the formation of a scab. 

" I have already subjected two hundred and eleven of 
my patients to the action of variolous matter, but every one 
resisted it. 

" The result of my experiments (which were made with 
every requisite caution) has fully convinced me that the 
true cow-pox is a safe and infallible preventive from the 
smallpox; that in no case which has fallen under my ob- 
servation has it been in any considerable degree trouble- 
some, much less have I seen any thing like danger; for in 
no instance were the patients prevented from following 
their ordinary employments. 

" In Dr. Woodville's publication on the cow-pox I notice 
an extraordinary fact. He says that the generality of 
his patients had pustules. It certainly appears extremely 
extraordinary that in all my cases there never was but 
one pustule, which appeared on a patient's elbow on the 
inoculated arm, and maturated It appeared exactly like 
that on the incised part. 

" The whole of my observations, founded as it appears 
on an extensive experience, leads me to these obvious 
conclusions; that those cases which have been or may be 
adduced against the preventive powers of the cow-pox 
could not have been those of the true kind, since it must 
appear to be absolutely impossible that I should have suc- 
ceeded in such a number of cases without a single ex- 
ception if such a preventive power did not exist. I cannot 
entertain a doubt that the inoculated cow-pox must quickly 
supersede that of the smallpox. If the many important 
advantages which must result from the new practice are 
duly considered, we may reasonably infer that public bene- 
fit, the sure test of the real merit of discoveries, will render 
it generally extensive. 

" To you, Sir, as the discoverer of this highly beneficial 
practice, mankind are under the highest obligations. As 
a private individual I participate in the general feeling; 
more particularly as you have afforded me an opportunity 



VACCINATION AGAINST SMALLPOX 221 

of noticing the effects of a singular disease, and of view- 
ing the progress of the most curious experiment that ever 
was recorded in the history of physiology. 

"I remain, dear sir, etc., 

"Joseph H. Marshall." 

"P.S. I should have observed that, of the patients I 
inoculated and enumerated in my letter, one hundred and 
twenty-seven were infected with the matter you sent me 
from the London cow. I discovered no dissimilarity of 
symptoms in these cases from those which I inoculated from 
matter procured in this country. No pustules have occurred, 
except in one or two cases, where a single one appeared 
on the inoculated arm. No difference was apparent in the 
local inflammation. There was no suspension of ordinary 
employment among the labouring people, nor was any 
medicine required. 

"I have frequently inoculated one or two in a family, 
and the remaining part of it some weeks afterwards. The 
uninfected have slept with the infected during the whole 
course of the disease without being affected; so that I 
am fully convinced that the disease cannot be taken but 
by actual contact with the matter. 

"A curious fact has lately fallen under my observa- 
tion, on which I leave you to comment. 

" I visited a patient with the confluent smallpox and 
charged a lancet with some of the matter. Two days 
afterwards I was desired to inoculate a woman and four 
children with the cow-pox, and I inadvertently took the 
vaccine matter on the same lancet which was before charged 
with that of smallpox. In three days I discovered the mis- 
take, and fully expected that my five patients would be 
infected with smallpox; but I was agreeably surprised to 
find the disease to be genuine cow-pox, which proceeded 
without deviating in any particular from my former cases. 
I afterwards inoculated these patients with variolous matter, 
but all of them resisted its action. 

" I omitted mentioning another great advantage that now 
occurs to me in the inoculated cow-pox; I mean the safety 
with which pregnant v/omen may have the disease com- 



222 EDWARD JENNER 

municated to them. I have inoculated a great number of 
females in that situation, and never observed their cases 
to differ in any respect from those of my other patients. 
Indeed, the disease is so mild that it seems as if it might 
at all times be communicated with the most perfect safety." 

I shall here take the oportunity of thanking Dr. Mar- 
shall and those other gentlemen who have obligingly pre- 
sented me with the result of their inoculations ; but, as they 
all agree in the same point as that given in the above 
communication, namely, the security of the patient from the 
effects of the smallpox after the cow-pox, their perusal, I pre- 
sume, would afford us no satisfaction that has not been am- 
ply given already. Particular occurrences I shall, of course, 
detail. Some of my correspondents have mentioned the ap- 
pearance of smallpox-like eruptions at the commencement 
of their inoculations; but in these cases the matter was 
derived from the original stock at the Smallpox Hospital. 

I have myself inoculated a very considerable number 
from the matter produced by Dr. Marshall's patients, origin- 
ating in the London cow, without observing pustules of 
any kind, and have dispersed it among others who have 
used it with a similar effect. From this source Mr. H. 
Jenner informs me he has inoculated above an hundred 
patients without observing eruptions. Whether the na- 
ture of the virus will undergo any change from being 
farther removed from its original source in passing suc- 
cessively from one person to another time alone can de- 
termine. That which I am now employing has been in 
use near eight months, and not the least change is per- 
ceptible in its mode of action either locally or constitu- 
tionally. There is, therefore, every reason to expect that its 
effects will remain unaltered and that we shall not be under 
the necessity of seeking fresh supplies from the cow. 

The following observations were obligingly sent me by 
Mr. Tierny, Assistant Surgeon to the South Gloucester 
Regiment of Militia, to whom I am indebted for a former 
report on this subject: 

" I inoculated with the cow-pox matter from the eleventh 
to the latter part of April, twenty-five persons, including 



VACCINATION AGAINST SMALLPOX 223 

women and children. Some on the eleventh were inocu- 
lated with the matter Mr. Shrapnell (surgeon to the regi- 
ment) had from you, the others with matter taken from 
these. The progress of the puncture was accurately ob- 
served, and its appearance seemed to differ from the small- 
pox in having less inflammation around its basis on the 
first days — that is, from the third to the seventh; but after 
this the inflammation increased, extending on the tenth 
or eleventh day to a circle of an inch and a half from its 
centre, and threatening very sore arms; but this I am 
happy to say was not the case; for, by applying mercurial 
ointment to the inflamed part, which was repeated daily 
until the inflammation went off, the arm got well without 
any further application or trouble. The constitutional symp- 
toms which appeared on the eighth or ninth day after 
inoculation scarcely deserved the name of disease, as they 
were so slight as to be scarcely perceptible, except that I 
could connect a slight headache and languor, with a stiff- 
ness and rather painful sensation in the axilla. This latter 
symptom was the most striking — it remained from twelve to 
forty-eight hours. In no case did I observe the smallest pustule, 
or even discolouration of the skin, like an incipient pus- 
tule, except about the part where the virus has been applied. 

"After all these symptoms had subsided and the arms 
were well, I inoculated four of this number with variolous 
matter, taken from a patient in another regiment. In 
each of these it was inserted several times under the cuti- 
cle, producing slight inflammation on the second or third 
day, and always disappearing before the fifth or sixth, 
except in one who had the cow-pox in Gloucestershire be- 
fore he joined us, and who also received it at this time 
by inoculation. In this man the puncture inflamed and 
his arm was much sorer than from the insertion of the 
cow-pox virus ; but there was no pain in the axilla, nor could 
any constitutional affection be observed. 

" I have only to add that I am now fully satisfied of 
the efficacy of the cow-pox in preventing the appearance 
of the smallpox, and that it is a most happy and salutary 
substitute for it. I remain, etc., 

"M. J. TlERNY.' 1 



224 EDWARD JENNER 

Although the susceptibility of the virus of the cow- 
pox is, for the most part, lost in those who have had the 
smallpox, yet in some constitutions it is only partially 
destroyed, and in others it does not appear to be in the 
least diminished. 

By far the greater number on whom trials were made 
resisted it entirely; yet I found some on whose arm the 
pustule from inoculation was formed completely, but with- 
out producing the common efflorescent blush around it, or 
any constitutional illness, while others have had the disease 
in the most perfect manner. A case of the latter kind 
having been presented to me by Mr. Fewster, Surgeon, of 
Thornbury, I shall insert it: 

" Three children were inoculated with the vaccine mat- 
ter you obligingly sent me. On calling to look at their 
arms three days after I was told that John Hodges, one 
of the three, had been inoculated with the smallpox when 
a year old, and that he had a full burthen, of which his 
face produced plentiful marks, a circumstance I was not 
before made acquainted with. On the sixth day the arm 
of the boy appeared as if inoculated with variolous mat- 
ter, but the pustule was rather more elevated. On the 
ninth day he complained of violent pain in his head and 
back, accompanied with vomiting and much fever. The 
next day he was very well and went to work as usual. 
The punctured part began to spread, and there was the 
areola around the inoculated part to a considerable extent. 

" As this is contrary to an assertion made in the Medical 
and Physical Journal, No. 8, I thought it right to give 
you this information, and remain, 

" Dear sir, etc., 

"J. Fewster." 

It appears, then, that the animal economy with regard to 
the action of this virus is under the same laws as it is with 
respect to the variolous virus, after previously feeling its 
influence, as far as comparisons can be made between the 
two diseases. 

Some striking instances of the power of the cow-pox in 



VACCINATION AGAINST SMALLPOX 225 

suspending the progress of the smallpox after the patients 
had been several days casually exposed to the infection have 
been laid before me by Mr. Lyford, Surgeon, of Winchester, 
and my nephew, the Rev. G. C. Jenner. Mr. Lyford, after 
giving an account of his extensive and successful practice in 
the vaccine inoculation in Hampshire, writes as follows : 

"The following case occurred to me a short time since, 
and may probably be worth your notice. I was sent for to 
a patient with the smallpox, and on inquiry found that five 
days previous to my seeing him the eruption began to appear. 
During the whole of this time two children who had not 
had the smallpox, were constantly in the room with their 
father, and frequently on the bed with him. The mother 
consulted me on the propriety of inoculating them, but object- 
ed to my taking the matter from their father, as he was 
subject to erysipelas. I advised her by all means to have 
them inoculated at that time, as I could not procure any 
variolous matter elsewhere. However, they were inoculated 
with vaccine matter, but I cannot say I flattered myself with 
its proving successful, as they had previously been so long 
and still continued to be exposed to the variolous infection. 
Notwithstanding this I was agreeably surprised to find the 
vaccine disease advance and go through its regular course; 
and, if I may be allowed the expression, to the total extinction 
of the smallpox." 

Mr. Jenner's cases were not less satisfactory. He writes 
as follows: 

"A son of Thomas Stinchcomb, of Woodford, near Berke- 
ley, was infected with the natural smallpox at Bristol, and 
came home to his father's cottage. Four days after the erup- 
tions had appeared upon the boy, the family (none of which 
had ever had the smallpox), consisting of the father, mother, 
and five children, was inoculated with vaccine virus. On the 
arm of the mother it failed to produce the least effect, and 
she, of course, had the smallpox, 8 but the rest of the family 
had the cow-pox in the usual way, and were not affected 
with the smallpox, although they were in the same room, 
and the children slept in the same bed with their brother 

5 Under similar circumstances I think it would be advisable to insert ihC 
matter into each arm, which would be more likely to insure the success of 
the operation. — £. J, 

(8) HC— Vol. 38 



EDWARD JENNER 

who was confined to it with the natural smallpox; and sub- 
sequently with their mother. 

"I attended this family with my brother, Mr. H. Jenner." 
The following cases are of too singular a nature to remain 
unnoticed. 

Miss R— — , a young lady about five years old, was seized 
on the evening of the eighth day after inoculation with vac- 
cine virus, with such symptoms as commonly denote the acces- 
sion of violent fever. Her throat was also a little sore, and 
there were some uneasy sensations about the muscles of the 
neck. The day following a rash was perceptible on her face 
and neck, so much resembling the efflorescence of the scarla- 
tina anginosa that I was induced to ask whether Miss R • 

had been exposed to the contagion of that disease. An an- 
swer in the affirmative, and the rapid spreading of the redness 
over the skin, at once relieved me from much anxiety respect- 
ing the nature of the malady, which went through its course 
in the ordinary way, but not without symptoms which were 
alarming both to myself and Mr. Lyford, who attended with 
me. There was no apparent deviation in the ordinary prog- 
ress of the pustule to a state of maturity from what we see 
in general ; yet there was a total suspension of the areola or 
florid discolouration around it, until the scarlatina had retired 
from the constitution. As soon as the patient was freed from 
this disease this appearance advanced in the usual way* 

The case of Miss H R is not less interesting than 

that of her sister, above related. She was exposed to the 
contagion of the scarlatina at the same time, and sickened 
almost at the same hour. The symptoms continued severe 
about twelve hours, when the scarlatina-rash shewed itself 
faintly upon her face, and partly upon her neck. After re- 
maining two or three hours it suddenly disappeared, and she 
became perfectly free from every complaint. My surprise 
at this sudden transition from extreme sickness to health in 
great measure ceased when I observed that the inoculated 
pustule had occasioned, in this case, the common efflorescent 

e I witnessed a similar fact in a case of measles. The pustule from the 
cow-pock virus advanced to maturity, while the measles existed in the con- 
stitution, but no efflorescence appeared around it until the measles had ceased 
to exert its influence. 



VACCINATION AGAINST SMALLPOX 227 

appearance around it, and that as it approached the centre it 
was nearly in an erysipelatous state. But the most remark- 
able part of this history is that, on the fourth day afterwards, 
so soon as the efflorescence began to die away upon the arm 
and the pustule to dry up, the scarlatina again appeared, her 
throat became sore, the rash spread all over her. She went 
fairly through the disease with its common symptoms. 

That these were actually cases of scarlatina was rendered 
certain by two servants in the family falling ill at the same 
time with the distemper, who had been exposed to the infec- 
tion with the young ladies. 

Some there are who suppose the security from the small- 
pox obtained through the cow-pox will be of a temporary 
nature only. This supposition is refuted not only by analogy 
with respect to the habits of diseases of a similar nature, 
but by incontrovertible facts, which appear in great numbers 
against it. To those already adduced in the former part of 
my first treatise 7 many more might be adduced were it deemed 
necessary; but among the cases I refer to, one will be found 
of a person who had the cow-pox fifty- three years before the 
effect of the smallpox was tried upon him. As he completely 
resisted it, the intervening period I conceive must necessarily 
satisfy any reasonable mind. Should further evidence be 
thought necessary, I shall observe that, among the cases pre- 
sented to me by Mr. Fry, Mr. Darke, Mr. Tierny, Mr. H. 
Jenner, and others, there were many whom they inoculated 
ineffectually with variolous matter, who had gone through 
the cow-pox many years before this trial was made. 

It has been imagined that the cow-pox is capable of being 
communicated from one person to another by effluvia without 
the intervention of inoculation. My experiments, made with 
the design of ascertaining this important point, all tend to 
establish my original position, that it is not infectious except 
by contact. I have never hesitated to suffer those on whose 
arms there were pustules exhaling the effluvia from associat- 
ing or even sleeping with others who never had experienced 
either the cow-pox or the smallpox. And, further, I have 
repeatedly, among children, caused the uninfected to breathe 
* See pages 217, 218. 219, 221, 223, etc. 



228 EDWARD JENNER 

over the inoculated vaccine pustules during their whole prog- 
ress, yet these experiments were tried without the least effect. 
However, to submit a matter so important to a still further 
scrutiny, I desired Mr. H. Jenner to make any further experi- 
ments which might strike him as most likely to establish or re- 
fute what had been advanced on this subject. He has since 
informed me "that he inoculated children at the breast, whose 
mothers had not gone through either the smallpox or the 
cow-pox; that he had inoculated mothers whose sucking in- 
fants had never undergone either of these diseases ; that the 
effluvia from the inoculated pustules, in either case, had been 
inhaled from day to day during the whole progress of their 
maturation, and that there was not the least perceptible effect 
from these exposures. One woman he inoculated about a 
week previous to her accouchement, that her infant might 
be the more fully and conveniently exposed to the pustule; 
but, as in the former instances, no infection was given, 
although the child frequently slept on the arm of its mother 
with its nostrils and mouth exposed to the pustule in the 
fullest state of maturity. In a word, is it not impossible for 
the cow-pox, whose only manifestation appears to consist in 
the pustules created by contact, to produce itself by effluvia ? 
In the course of a late inoculation I observed an appear- 
ance which it may be proper here to relate. The punctured 
part on a boy's arm (who was inoculated with fresh limpid 
virus) on the sixth day, instead of shewing a beginning 
vesicle, which is usual in the cow-pox at that period, was 
encrusted over with a rugged, amber-coloured scab. The 
scab continued to spread and increase in thickness for some 
days, when, at its edges, a vesicated ring appeared, and the 
disease went through its ordinary course, the boy havinp had 
soreness in the axilla and some slight indisposition. With 
the fluid matter taken from his arm five persons were inocu- 
lated. In one it took no effect. In another it produced a 
perfect pustule without any deviation from the common 
appearance; but in the other three the progress of the in- 
flammation was exactly similar to the instance which afforded 
the virus for their inoculation ; there was a creeping scab of 
a loose texture, and subsequently the formation of limpid fluid 
at its edges. As these people were all employed in laborious 



VACCINATION AGAINST SMALLPOX 229 

exercises, it is possible that these anomalous appearances 
might owe their origin to the friction of the clothes on the 
newly inflamed part of the arm. I have noj: yet had an 
opportunity of exposing them to the smallpox. 

In the early part of this inquiry I felt far more anxious 
respecting the inflammation of the inoculated arm than at 
present ; yet that this affection will go on to a greater extent 
than could be wished is a circumstance sometimes to be ex- 
pected. As this can be checked, or even entirely subdued, by 
very simple means, I see no reason why the patient should 
feel an uneasy hour because an application may not be abso- 
lutely necessary. About the tenth or eleventh day, if the 
pustule has proceeded regularly, the appearance of the arm 
will almost to a certainty indicate whether this is to be ex- 
pected or not. Should it happen, nothing more need be done 
than to apply a single drop of the aqua lythargyri acetate 
upon the pustule, and, having suffered it to remain two or 
three minutes, to cover the efflorescence surrounding the pus- 
tule with a piece of linen dipped in the aqua lythargyri 
compos. 9 The former may be repeated twice or thrice during 
the day, the latter as often as it may feel agreeable to the 
patient. 

When the scab is prematurely rubbed off (a circumstance 
not unfrequent among children and working people), the 
application of a little aqua lythargyri acet. to the part imme- 
diately coagulates the surface, which supplies its place, and 
prevents a sore. 

In my former treatises on this subject I have remarked 
that the human constitution frequently retains its susceptibil- 
ity to the smallpox contagion (both from effluvia and contact) 
after previously feeling its influence. In further corrobora- 
tion of this declaration many facts have been communicated 
to me by various correspondents. I shall select one of them. 

"Dear Sir: 

" Society at large must, I think, feel much indebted to 
you for your Inquiries and Observations on the Nature and 
Effects of the Variolas Vaccinas, etc., etc. As I conceive 

8 Extract of Saturn. 

9 Goulard water. For further information on this subject see the first 
Treatise on the Van Vac, Dr. Marshall's letters, etc. 



230 EDWARD JENNER 

v/hat I am now about to communicate to be of some im- 
portance, I imagine it cannot be uninteresting to you, espe- 
cially as it will serve to corroborate your assertion of the 
susceptibility of the human system of the variolous con- 
tagion, although it has previously been made sensible of its 
action. In November, 1793, I was desired to inoculate a 
person with the smallpox. I took the variolous matter 
from a child under the disease in the natural way, who 
had a large burthen of distinct pustules. The mother of 
the child being desirous of seeing my method of communi- 
cating the disease by inoculation, after having opened a 
pustule, I introduced the point of my lancet in the usual way 
on the back part of my own hand, and thought no more of 
it until I felt a sensation in the part which reminded me 
of the transaction. This happened upon the third day; on 
the fourth there were all the appearances common to inocu- 
lation, at which I was not at all surprised, nor did I feel 
myself uneasy upon perceiving the inflammation continue to 
increase to the sixth and seventh day, accompanied with a 
very small quantity of fluid, repeated experiments having 
taught me it might happen so with persons who had under- 
gone the disease, and yet would escape any constitutional 
affection; but I was not so fortunate; for on the eighth day 
I was seized with all the symptoms of the eruptive fever, 
but in a much more violent degree than when I was before 
inoculated, which was about eighteen years previous to 
this, when I had a considerable number of pustules. I 
must confess I was now greatly alarmed, although I had 
been much engaged in the smallpox, having at different 
times inoculated not less than two thousand persons. I 
was convinced my present indisposition proceeded from the 
insertion of the variolous matter, and, therefore, anxiously 
looked for an eruption. On the tenth day I felt a very un- 
pleasant sensation of stillness and heat on each side of my 
face near my ear, and the fever began to decline. The af- 
fection in my face soon terminated in three or four pustules 
attended with inflammation, but which did not maturate, and 
I was presently well. 

"I remain, dear sir, etc., 

"Thomas Miles/' 



VACCINATION AGAINST SMALLPOX 231 

This inquiry is not now so much in its infancy as to re- 
strain me from speaking more positively than formerly on 
the important point of scrophula as connected with the 
smallpox. 

Every practitioner in medicine who has extensively in- 
oculated with the smallpox, or has attended many of those 
who have had the distemper in the natural way, must ac- 
knowledge that he has frequently seen scrophulous affections, 
in some form or another, sometimes rather quickly shewing 
themselves after the recovery of the patients. Conceiving 
this fact to be admitted, as I presume it must be by all who 
have carefully attended to the subject, may I not ask whether 
it does not appear probable that the general introduction of 
the smallpox into Europe has not been among the most 
conductive means in exciting that formidable foe to health? 
Having attentively watched the effects of the cow-pox in 
this respect, I am happy in being able to declare that the 
disease does not appear to have the least tendency to pro- 
duce this destructive malady. 

The scepticism that appeared, even among the most en- 
lightened of medical men when my sentiments on the im- 
portant subject of the cow-pox were first promulgated, was 
highly laudable. To have admitted the truth of a doctrine, 
at once so novel and so unlike any thing that ever had ap- 
peared in the annals of medicine, without the test of the 
most rigid scrutiny, would have bordered upon temerity ; but 
now, when that scrutiny has taken place, not only among 
ourselves, but in the first professional circles in Europe, and 
when it has been uniformly found in such abundant instances 
that the human frame, when* once it has felt the influence 
of the genuine cow-pox in the way that has been described, 
is never afterwards at any period of its existence assailable 
by the smallpox, may I not with perfect confidence con- 
gratulate my country and society at large on their beholding, 
in the mild form of the cow-pox, an antidote that is capable 
of extirpating from the earth a disease which is every hour 
devouring its victims; a disease that has ever been con- 
sidered as the severest scourge of the human race ! 



BOSTON COLLEGE 




3 9031 026 12390 1